RE: Tire pressure on dually
If you give the maximum load and pressure printed on the sidewalls of your tires , and from the cars the GAWR's ( Gross Axle Weight Ratings), I can fill them in my motorhomeRV tirepressure-calculator spreadsheet.
Will give a picture included of it, in my answer then.
But pressure advice is all about load on the seperate tires.
And for the 2500 the GAWR back is devided over 2 tires yust as front so needs higher pressure at back then front, because back-axle GAWR is more.
For the 3500 the more GAWR is devided over 4 tires wich needs lower pressure , even when using the DUAL maximum load.
That is the reason why the 3500 can do with lower pressure at back.
RE: RV Shakes and Bumps, Rattles & Rolls - Upgrades
As long as you did not weigh the seperate axles or better even 4 point weighing, you have to do with the GAWR's ( Gross Axle Weight Ratings).
From the tires you need maximum load and pressure needed for that , written on sidewall.
If you then put those data in my RV tire-pressure-calculator , it might even give lower pressure then the 10 lower you want to trie, and 10 would not give the comfort your wanted, so you stripe away the pressure adjusting, and spend money on things you probably dont need.
On the other hand, if for instance the back axle needs that maxloadpressure, wich is not the maximum pressure of the tire,or a bit higher, you damage the tires by riding with that 10 psi lower.
So first do some calculation, and then trust that.
If you rather look in a list and dont want to use my calculator, I also made lists wich give lower loadcapacity for the pressure then the American lists and even lower then the European lists, and takes care the deflection of the tire stays the same as when maximum load and this pressure needed for that on the tire, wich is the goal of all the calculations. But if you look the loads back in the list, first add up to 10% to it before looking back for savety margin, without loosing to much comfort and gripp. I concluded from reactions, that if the real weight is less then 85% of the loadcapacity belonging to the used pressure, discomfort begins by bouncing, but is discussable.
Over 100% gives tire damage at higher speed, but comfort and gripp even get better, so it is tempting to go to lo, when lowering until you reach a good comfort.
Steering will get a bit heaviër when using lower pressure , but gives probably better feeling for you.
Map with my tire-pressure calculator
Map with presssure/loadcapacity-lists saver then the ones you find on internet
RE: tire pressure on transforce ht tires
I made my own pressure/loadcapacity lists wich comes to lower loadcapacity for the pressure then the American lists, and even lower then the saver European lists.
Michelin adyust their lists to the American system of TRA, so those lists also give to high loadcapacity's
Planted PDF's for it at next map on my skydrive of hotmail adress.
Pressure/loadcapacity lists take the USA map
For that you first have to see what maxloadpressure your tires have.
If you read "maximum load xxxx lbs AT yyy PSI ( cold)" then the yyy is the pressure needed for the maximum load, and not the maximum pressure of the tire. Probably its 80 psi but can be different.
Then open the file in my map with 80psi beginning.
Search at front for the maximum load in lbs or the loadindex, and look the weights up , but first add 10% to it for savety-margin.
Made seperate lists for per tire and singleaxle and dualaxle, so you dont have to do the division yourselfes. Rear you probably have dual so 4 tires on one axle, front single ( 2 tires on the axle).
But if you give the tire-specifications and axle/tire combinations , I can put that in my tire-pressure calculator, and it calculates a save pressure.
RE: Proper tire pressure?
Then you first have to calculate what the minimum pressure is for the loads on the tires.
If your tires are overrated, wich I think they are not, you can use lower pressure.
If the tires are yust enaugh , you are even allowed to go 10psi over that 50 psi, because its not the maximum pressure of the tire.
If your friend lowers the presssure until it feels good, he probably lowers under the border at wich the tires are save.
Gripp and comfort get even better if your pressure is below the damage border, but at a sertain moment you get an accident by blowing tire.
So give the GAWR's and GVWR of the trailer and number of tires that load is resting on, and the maximum load and pressure-rating ( Probably C-load/6ply because of the AT pressure of 50 psi) , and I will calculate with spreadsheet i made , a pressure with some reserve for little overloading and unequal loading R/L.
It is always better to weigh the vehicle, but if you havent , we have to do with the GAWR's and GVWR( gross vehicle weight rating).
RE: Low Tire Pressure
What you can do is, if you have a bicycle-pump with an adaptor to car-tires, pump the tires with that pump.
Will take 100 times pumping , but can do in this special situation.
bycicles also use high pressure, especially race-bycicles.
Some pumps even have a manometer on it, so you can see the pressure.
You can also use it on the road , because then its only to add a few psi , wich takes only 20 times pumping. And it always works , no need for electricity and good for your condition.
RE: Adjusting tire pressure for load
http://www.goodyeartrucktires.com/pdf/resources/publications/2010_loadinflation.pdf
The source is the Tire and Rim Association, so it should apply to all manufacturers.
I already stumbled on this article, and it shows at the bottom of page 1 that the pressure most think is the maximum is in fact the minimum required presure for the maximum load.
TRA allows even 10 psi for LT tires above that, and for truck tires even 20 psi above that maxloadpressure as I saw it called also.
so dont be afraid to go over the fi 80 psi if that is the pressure printed on the sidewall ( E-load/10plyrating).
for topic starter this all is not the issue.
Page 2 even gives at lower speed 9% addition above maximum load without highening up the pressure.
RE: Adjusting tire pressure for load
Using my spreadsheet i come to 64F and 49 back, and I use my own formula that gives a bit lower pressure then linear math. This is higher then your linear math because I add 10% reserve to the load first.
These pressures wont give damage to the tires, assuming your given weights are right, and thats the tricky point here, but you realise that , I make of your story.
The tires stability is yust how you feel it, a little swaying wont say that the car is dangerously unstable, is my opinion.
Nowadays cars are made that stiff, that we have gotten used to the discomfort, wich a stiffer tire gives, but before 2000 the tiremakers also gave minimum advices.
Here a picture of the spreadsheet but will also give the link to the map where you can download the spreadsheet, search for 4xMike,
Then you can chanche things or add in dark blue the GAWR's and to use reserve % , wich is now set on 10% standard.
https://x3mzhq.blu.livefilestore.com/y2pkEUtJsB40BW4dhcYIkaoO9U8HHZVZGek2dSF5iW6xfolemqtSLEJJVr2e1HvsFunMQheCckGuswLuyZLJZ5CTbxBm_mgx5gc51C-cjqFHJzevcZN4B2TLhqkzHjswdhy/4xMikeRVTPC.GIF?psid=1
Now the link to the map.
The examples map with the spreadsheet 4XmikeRVetc.
See what you can do with it.
RE: Wandering Nightmare
Once read somewhere that you must have at minimum 30% of the total load at the front wheels, so if you ever weigh, calculate if it is below or above that.
With that large overhang I expect mayby even much lower then 30% on front, so it sertainly can explain the complaints you have.
Also with that large overhang , mind that things behind the rear-axle give more weight on the rear axle then the weight that is placed because of the leaver-effect, and lifts up the front.
What you can try , if weighing prooves this all, is to replace some heavy things like watertank if possible , beween the axles as much to the front as possible.
Also mind the tire-pressures, high at back and low at front
Back even higher then the maxloadpressure printed on sidewall.
TRA allows 10psi higher for LT tires and 20psi higher for truck tires.
So if the pressure yyy in "maximum load xxxx lbs AT yyy psi(cold)"is fi 80 psi then you may fill to 90 psi, and it is supported by the tire-makers, they cant sew you for it. At lower speed even more then maximum load of tire is supported by the TRA.
My advice is also to weigh , then you will be surprised of the overloading of the rear-axle and low load on front, is my prediction.
RE: tire pressure for towing 2008 dutchmen colorao FW
You have a dutchmen but I am a dutchman so explain what FW stands for ( Folding Wagon mayby).
And what does the 0.1/10 means.
ST ( special trailer) tires are kept to that 80 psi for E-load/ 10plyrated for the next reasons.
They are calculated in their maximum load for a lower speed, so the tire is allowed more deflection, wich gives a larger surface on the ground.
Second is , and that is my own conclusion, because they often have other profile, large profile blocks that cover a part of the sidewall, wich shorten the free flexible part of that sidewall,so less deflection is save for the tire, wich leads to lower maximum load then the tire-maker calculated, because they assumed more deflection.
First reason is often used, but this makes the reserves above given maximum load marginal.
Second reason means that you have to substract about 20% of the maximum load, before calculating the tire-pressure, to bring back the reserves a normal car tire has.
This together makes that the load on the tires comes close to the maximum load the tires may have to laws of nature, especially when you are unequally loaded R/L ( for 1 tire then)
This does not mean that if the tires are oversised, and you have a verry light trailer, you have to keep to 80 psi.
But also if your loads are at the max, you may even go over the 80psi, TRA allows 10 psi , but does not support higher loads for that.
What I need is the GVWR ( gross vehicle weight rating) of your FW, and the number of tires on the ground when driving ( so not the spare), and the number of axles. your tires I could not find with google, so look on the sidewal what the maximum load is, searching saw the rimm-sise of 11 ,pooh thats small, but means that the maximum load will be low. Or could it be you miswrote the rimm-sise, again googling a picture I saw your colorao is a verry large 5thwheeler with tandem-axles.
If you give me that I will calculate a pressure that is save for the tires, including all the factors I described.
Estimate that the advice will be above 80 psi, because your FW has low weight , but the maximum load of the tires is also low.
Edit: here I found maxis tires and the only trailer tire with 235/80 was a 16 inch rimm with Loadindex of 124 wich stands for 1600kg/3527lbs maximum load. so this is know , if its richt, check it.
then I only need the vehicle specifications, if you ever weighed per axle or beter per wheel, those loads and tonge-weigt .
Saw other mis-writing I think Colorao must be Colorado I think.
RE: Max tire pressure vs Load on tires
I always follow the tire load chart. The tough part is knowing the load on my cargo trailers.
I may have to make a chart of spring sag vs load so I know the load at any time. Like a Plimsoll line on a boat.
You could also use the deflection of the tire.
Idea is that the sidewall may deflect maximum 20% of the free flexible part of it . This is for a 80% hight/width (aspect ratio=AR).
Only thing you need is a perfect flat and water-leveled underground, and that is hard to find.
If you look in a tire load chart , then look in the list I made, so you dont loose a part of the carrefully deterimined reserve, by the to high given loadcapacity in the lower pressures on the american charts.
RE: Max tire pressure vs Load on tires
Inflate to what is indicated on the sidewalls. If the weight on the tires is more than what the tires are designed for then you are overloaded.
Amd if you are overloaded, what do you have to do then, stop driving and leave it standing?
Practice is that a little overloading easyly happens at RV's.
If then you yust highen up the pressure within the limits that are allowed , you can savely drive with a lower speed.
RE: Max tire pressure vs Load on tires
When you weighed per wheel, you can use part 3 of my camperRVtyrepressurecalculator. In that I use formula that leads to even higher pressure then the European calculation of the tyre makers.
In next map on my skydrive of hotmail adress, you can find it, always take the newest version and they are in xlsx and xls so also for older Excell to use.
Download by RIGHTclicking on it and choose download in the dropdownbox.
After eventual viruscheck, open in Excell or OO Calc to use it.
Mind to check the weight kinds.
RV tire pressure calculators
But mind that if they are trailer-tires they are as already written here, calculated for lower speed, so allowed more deflection, and have no reserve built in. If then the profile is of an off-road kind and covers a part of the sidewall, that sidewall may flex less then the tire-makers used for their calculation of the maximum load, wich makes the needed pressure even higher.
So if you have them you can substract even up to 20% of the maximum load beforre filling in.
In part 3 of that spreadsheet I go from same pressure R/L and lowest use of the loadcapacity for the pressure of 85% and highest of 95%, so with some reserve still for , pressure-loss in time, loadshifting during vacation,misreadings of load and pressure scales.
But if you rather use a list to look back in you can find it in next map on my skydrive.
They are in PDF so can be left-clicked too. you can choose the right PDF by the name of it, beginning with the maxloadpressure wich is not the maximum pressure of the tire. AT the end pick "tire" for given per tire, "Axlesingle" for given per single axle so 2 tires , and " AxleDual" for given per dual-axle so 4 tires , so you dont have to do that calculation yourselfes. determining the right loads to search back is your own responcibility, but this is also the case in the first spreadsheetsmap.
Extasave pressure/loadcapacity-lists
The lists are made with my own formula that leads to lower loadcapacity for the pressure then the American way and even the European way of calculating, and to my opinion takes care that the deflection of the tire stays the same over the whole pressure/loadcapacity-range.
Also higher then maxloadpressure is given , because you may go over that "maximum load xxxx lbs AT yyy PSI ( cold)" in wich yyy is the maxloadpressure, called reference-pressure in the official formula. So if the outcome is 10 psi higher it is allowed by TRA for LT and trailer tires.
But if you cant work it out, give me the tire-loads and maxload and maxloadpressure of the tire, and I will do it for you.
RE: Need a little advice.
@ AZ T&T your 115 lbs is about the same as used in Europe 110 to 120 Nm. Coincidence??
For the tire-pressure you could use spreadsheet I made, if you have Excell or Open Office Calc on your computer.
Otherwise give the GAWR's ( Gross Axle Weight Ratings) front and back.
Beter would be, if you weighed fully loaded, those axle, or better seperate wheel weights.
And from the tires the maximum load , the 80 psi is already given, is called the reference Pressure and is not the maximum pressure.
You may even go over that , for LT tires 10 psi and truck-tires 20 psi.
No extra load is supported though by the tire-makers, only for low speed.
When you search on the sidewall for the maximum load or loadindex, also see if there is an additional loadindex with a lower speedcode letter.
Then the tire-maker even supports that higher load with the same pressure, but only for that lower speed the letter stands for.
Speedcode N= 140km/85m/h and J=100km/60 to 65m/h
If you want to do it yourselfes, here the link to the map.
RV tire pressure calculator
Always pick the newest version, and they are given in XLS( older versions of Excell) and XLSX.
Click right( so not left) and choose download from the dropdownbox.
After download and eventual virus-check, open in Excell or OOC .
Mostly if you yust click on it , it is automatically openend in Excell, if you have it on the computer.
If you rather look it up in a list, use those in next map.
The loadcapacity there is lower then the American lists give, and even lower then the European lists for larger tires.
To my opinion , my calculation takes care that the deflection of the tire stays the same over the whole range of pressure/loadcapacity range, wich is the goal of all the different calculations.
If your loadindex/maximum load is not in the list, write it here , and a make a new one.
Pressure/Loadcapacity-lists
You can see wich list to use by the name of it beginning with the referencepressure then loadindexes and last for tire/axle single and axle dual. In America it is always give per tire, but the for the axles the times 2 and 4 is done for you. You would need the 80psi100li143axlesingle.
Mind to add a reserve to the loads you weighed ,I advice 10% extra but up to 18% wont even give bumping ( my conclusion so discussable)and gives maximum reserve for ,, pressure-loss in time, unequall loading R/L, misreadings of load and pressure-scales, what I might have forgotten.
If you use the list the determination of the right load is your responcibility.
RE: Air pressure...what's the correct amount?
If the tires are load rated at 80 PSI I would run them at 80 PSI for all the load bearing tires (trailer tires and truck's rear tires). You will get the least sidewall flexing and they will run cooler and last longer and provide better handling.
It is a mistake to go by the manufacturers' charts to determine the proper air pressure to use. If a truck's manufacturer puts on load range E tires and the truck manufacturer recommends 65/80 that is what you should use with that type of tire.
At lower pressures there will not be even contact with the road surface and the tires will wear faster at the edges. There will also be more tire flexing and this also shortens tread life and makes the tires run hotter and increase the odds for a blowout.
This is in effect what happened with the Bridgestone tires on the Ford Explorers where Ford's engineers changed the recommended inflation for the tires to compenstate for suspension design flaws and so people were driving the SUV's with underinflatted tires and the end result was a great many blowouts that often result in the deaths of the SUV's occupants.
About the Bridgestone tires on the Ford Explorer, the story is a little different. also for those tires a lower pressure then written on the sidewall was allowed.
At first I thougt the calculation was wrong, and it was, but was repeared by substracting 10 of the maximum load.
Later I came to the conclusion, bij an article of Capri-Racer ,in wich a tipical cavity patern under the treath, that the maximum load of such a off-road-looking tire , with large profile-blocks that cover a part of the sidewall, was calculated to high by the tire-maker.
RE: Want to switch tires from ST to P
Been searching for a tilting caravan on youtube .
Came to a germain spoken film , but that does not matter, its only to show the tilting.
http://www.youtube.com/watch?v=uLJr7DB7eak
RE: Want to switch tires from ST to P
So I made a new picture again with the 2700 lbs, and came to 50psi exact.
So probably the blow out was yust because of a puncture.
Did you have many blow outs with the original tires?
For this topic I was searching for a reason for the blow out in to low advice-pressure or maximum load. But probably it was yust an accident.
But we became both wiser about the axle and tonge-weight.
https://jbh17w.bn1.livefilestore.com/y1poSDqbvj5VcZ9Zp5ilHrFmEYm_H9ulj7BfNRbik6WQWs6DMDIb6oT-phTXFWy4nX8STX4Q1k8Yh3_MXfwwRtZP3nZYB4FXymy/175R13SToriginaltires.GIF?psid=1 height=400 width=600
RE: Want to switch tires from ST to P
2 Propane tanks of only 7 liter at the front in the disselcompartiment ( probalby wrong word, the thing that is open at the front at the first picture).
then even a bicycle rack at the back with 2 bikes of total 90 to 100 lbs . Some have a bicycle rack on the front on the "Dissel"to get more weigth on the front. And nowadays we have electric bicycles of about 55 lbs each.
Whe had all the heavy stuff like outside tables and chairs on the roundsit wich we transformed to bed, Also to give the front more weight.
Think we had about 120 lbs on the hook, so if the 1300kg/2860 lbs was realy the weight it would have been a poor 5 % .
RE: Want to switch tires from ST to P
Asuming you weighed fully loaded, what maximum load and referencepressure( maxload xxxx lbs AT yyy psi(cold) did the original tires have and what pressure did you use.
ST tires are made with same referencepressure as normal car tires(35 psi) up to E load ( 80 psi). so wich where they.
Looked at the picture and yes the axle is more to the back.
Found a picture of my caravan, wich i sold last year to show the axle placement
https://jbii2a.bn1.livefilestore.com/y1pZ9DkDRk4NduvGlT0mVuD8nEj5RbfBCTY8L6MSS46fOaGeiceaJXLujEpnof4poHYLiUhVWAkwsivxjfJl6OrWExCuiRn4zzf/DSC00979.JPG?psid=1 height=200 width=300
and one from the front to show the length of the "dissel" as we call it.
The wheels are placed almost in the middle of the box.
Here the front
https://jbii2a.bn1.livefilestore.com/y1p9za9rj_ODbwjoKfk-w2WlfpWPNNICR_nG2RIxWi9mvpR20xAMhP6FzqJhsW4BI53nxk5lIZ8maQ90hVl8cdD2EmRw9CT-L_c/DSC00943.JPG?psid=1 height=200 width=300
RE: Want to switch tires from ST to P
@ Dannydimmit
They only give an lowest limit of 1% by law, but maximum is not given.
Fact in Europe is that the tow bar of cars are not allowed to carry more then 50kg/110lbs to maximum rarely 100kg /220lbs.
Must have something to do with the construction of modern cars, I think.
The construction of Caravans( so TT is travel-Trailer and not Tent-trailer , thanks for this correction)shal be made, so the tongweight does not get to high, in contrary to America.
We have a site called "caravantrekker" that gives advices about towing and car-TT combinations.
They advice minimum of 5% tong weight , thoug they say that above 10% would be more ideal. But also the hight of the gravity-point is important. If that is low placed, the TT gets more stabyle.
Well, on our little 2011 Ford Focus the hitch is rated 200 pounds
of tongue weight , and 2000 pounds gross trailer weight.
On our 2003 Dodge 2500 pickup the weights vary by a incredible amount depending on which type of hitch that is on the truck
Class I – 2000-lbs. GTW, 200-lbs. TW
Class II – 3500-lbs. GTW, 350-lbs. TW
Class III – 6000-lbs. GTW, 600-lbs. TW
Class IV & Class V – 18,000-lbs. GTW, 1800-lbs. TW (GTW = Gross Trailer Weight, TW= Tongue Weight)
of course a load distributing hitch with anti sway bars are almost always used with a larger travel trailer. but on bumper pulled lowboy type trailers that are used to haul farm tractors , machinery or building materials the weight distrusting hitch is almost never used .
The bigger the % of the gross trailer weight thats on the tongue equates to a better trailing trailer.
In my calculator, I just recently chached something in the tong-weight,
Made it , together with the weight and speed-kind , that change with the language , to change with that language, and made a new language called "American English" and putted this percentage to 9% for America and 4% for the other European languages.
But in the picture I gave in orange the fixed tonge weight of 150 for the last one, so overruled this part.
This can better be to low so there is more weight supposed on the axle, and gives a higher pressure advice, wich is never bad, better to high then to low. In the first advice for the P-tires I used 100lbs even and 36 psi reference-pressure wich is for European tyres ,for American it is 35 psi, but this also only gives higher pressure advice.
Also added again in orange a what if real weight is higher of 100 lbs, with the used pressure-advice. It gives 183lbs weightdifference L/R before tire-damage happens ( on the most loaded side).
A weigtdifference of 80kg/175lbs can easyly happen for TT, with for instance kitchen on one side.
So in case of daubt, always use the highest load, and reference-pressure( wich is not the maximum pressure) and the lowest maximum load.
Also for tandem axle, better use the maximum load for twinwheel axle for higher advice , thoug I never found any proove that it should be used.
But what I understand from your replie, is that the TT's for american marked have the axle further to the back, so it gives more % tonge-weight. But to what weight are the towbar restricted mostly in America? There must be a limit too.
So tonge-weight is always 10% of maximum to tow weight.
In Europe the car maker has to have the car tested, for a weight they themselves determine. The car -TT combination must drive away from standing still for 3 times on a roadpercentage of 12% ( uphil) to pass the test. This gives difference between brands. One brand calculates better and has higher towing weight approved then another who presents it on the low side to the test.
My car , a Seat Alhambra Diesel 2.0 ( nephew of Ford Galaxy)has a maximum allowed towing weight of 2000kg/4400 lbs, and the tow-barr has a plate with maximum of 80kg/175lbs. So this is about only 4% .
I towed a TT of 1300kg/2860lbs with it on the Frence toll roads, wich are high quallity asphalt roads with speeds of max 110km/little 70 m/h ( is allowed there)and had no problems, but felt the TT pulling when going besides trucks. In Holland since recently 90km/55m/h is allowed now only on the highroad, rest is as it was 80km/50m/h.
But also at 50m/h on the bad roads near Luik/Liege(Belgium) only had the top wheel fibrating to the ground, but no stability problems.
Also depends on the ratio car-TT wich was good for my combination.
The tow bar has a plate with the maximum to tow weight, though some go a bit over that for better balance. I dont know for shure but police can give a penalty for that , if you go over it.
But the construction of American Tow-bars must be much heavyer then that of European to carry that larger weight.
Edit: saw your correction after I placed my reply, but had puzzled it out already.
RE: Want to switch tires from ST to P
@ Dannydimmit
They only give an lowest limit of 1% by law, but maximum is not given.
Fact in Europe is that the tow bar of cars are not allowed to carry more then 50kg/110lbs to maximum rarely 100kg /220lbs.
Must have something to do with the construction of modern cars, I think.
The construction of Caravans( so TT is travel-Trailer and not Tent-trailer , thanks for this correction)shal be made, so the tongweight does not get to high, in contrary to America.
We have a site called "caravantrekker" that gives advices about towing and car-TT combinations.
They advice minimum of 5% tong weight , thoug they say that above 10% would be more ideal. But also the hight of the gravity-point is important. If that is low placed, the TT gets more stabyle.
In my calculator, I just recently chached something in the tong-weight,
Made it , together with the weight and speed-kind , that change with the language , to change with that language, and made a new language called "American English" and putted this percentage to 9% for America and 4% for the other European languages.
But in the picture I gave in orange the fixed tonge weight of 150 for the last one, so overruled this part.
This can better be to low so there is more weight supposed on the axle, and gives a higher pressure advice, wich is never bad, better to high then to low. In the first advice for the P-tires I used 100lbs even and 36 psi reference-pressure wich is for European tyres ,for American it is 35 psi, but this also only gives higher pressure advice.
Also added again in orange a what if real weight is higher of 100 lbs, with the used pressure-advice. It gives 183lbs weightdifference L/R before tire-damage happens ( on the most loaded side).
A weigtdifference of 80kg/175lbs can easyly happen for TT, with for instance kitchen on one side.
So in case of daubt, always use the highest load, and reference-pressure( wich is not the maximum pressure) and the lowest maximum load.
Also for tandem axle, better use the maximum load for twinwheel axle for higher advice , thoug I never found any proove that it should be used.
But what I understand from your replie, is that the TT's for american marked have the axle further to the back, so it gives more % tonge-weight. But to what weight are the towbar restricted mostly in America? There must be a limit too.
