jeshoffstall wrote: Sorry guys, did not mean to confuse the issue - I meant going from a P rated tire to an LT tire. Looking at Michelin's site, I see they now make an LT tire in the same size as my current P rated tire.
Specs are:
P rated, P275/65R18, max load 2365@44 psi
LT rated, LT275/65R18/E, max load 3415@80 psi
My TT has a dry weight of 4,991, GVWR of 6,550 and a dry tounge weight of 597 (have not yet got the rig on the scales).
Possibly the LTs are overkill?
Thanks,
Jack
So much out of context
Maybe this break down on the different classes and metrics might help
There are different 'classes' of tires. Below list is from the lowest
to the highest
ST, are trailer tires and has a 65mph limit
P, are passenger CAR tires
LT, are light truck tires
Commercial, are for the semi's
off road, are those you see on hugmongo dump trucks...those tires are in the 8 feet/dia range
Then their load ratings.
'P' class tires use a numeric designation that has a specific weight rating in pounds
'LT' class has a ply rating and goes back to the days when they actually has that many number of plys (today's only has 2-3, generally) and are going to the numeric ratings (too confusing to so many)
'Commercial' and 'ST' also use
ply ratings
Then folks taking the letter ply rating as if it is an end all are
taking it out of context.
An 'E' by itself has no meaning without the size, other than it is a 10 ply rating
Then it's not just the weight rating, but the class that makes the
biggest difference.
Also note that a 'P' class tire used on a pickup/SUV must be de-rated
a min of 9%. The OEM's have already done that with the 'P' class tire
they supplied with most all half ton trucks/SUVs (except for the fake
half tons with a +8K GVWR)
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...
You're going to end up running the LT-E rated tires underinflated, and at well below their rated capacity, on the stock rims.
I used to run LT-rated tires on my 1/2 ton in the winter.
The 225-75R16 LT-E rated snows are rated at ~2800lbs each at 80PSI.
The 235-75R16 P rated OEM tires are rated at 2094lbs each at 44PSI.
800lbs difference, yes, at a pressure I could not achieve with the stock rims. At 40PSI both tires ended up with roughly the same weight carrying capacity (around 2000lbs each).
2002 Chevy 3500 DRW 8.1L/Allison
2000 Palomino B1500
...and the reason why I need a DRW to haul a Palomino:
2004 United 7x14 tandem axle enclosed toy trailer
2011 PJ 8x20 7-ton deckover equipment trailer
mkirsch wrote: You're going to end up running the LT-E rated tires underinflated, and at well below their rated capacity, on the stock rims.
I used to run LT-rated tires on my 1/2 ton in the winter.
The 225-75R16 LT-E rated snows are rated at ~2800lbs each at 80PSI.
The 235-75R16 P rated OEM tires are rated at 2094lbs each at 44PSI.
800lbs difference, yes, at a pressure I could not achieve with the stock rims. At 40PSI both tires ended up with roughly the same weight carrying capacity (around 2000lbs each).
Thank you - that is the most clarity I have seen on the issue. I also email Michelin directly to get their advice, but will probably just stick with P rated tires since I not over capacity now.
I'm getting LT tires tomorrow.. You can email the manufacturer to find out what PSI you need to get 2600lbs (max load of the stock tires) of load capacity out of the tires. Using Goodyear's load tables it's 55psi for 2660lbs for a LT275/65-18, but YMMV.
For reference the Tundra Rock Warrior comes with LT tires (17 inch) and they run them at 46psi when not towing.
Don't make the mistake of thinking that the LT tires will only need 30psi like the door placard says.
- Ken
2010 Toyota Tundra 5.7 CrewMax Limited, TRD Swaybar, Timbrens, Bilstein HD shocks
2012 Keystone Sprinter 272BHS
Reese DC Sway, Fastway Flip, Tekonsha P3
Yamaha 2400iSHC Generator
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My Tundra currently has P 275/65 R 18 tires and the door jamb sticker shows 31
PSI front and 33 PSI rear.
Want I want to do is upgrade to the M/S 2 LT 275/65 R 18 (same size tire,
but in higher weight rating) to increase stability while pulling a trailer.
I was interested in what PSI I should use for the LT tires vs. the current P
rated tires on my vehicle? I see folks on internet forms running 50-60 PSI
in these tires, but would like Michelin's recommendation.
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The minimum recommended PSI for the LT275/65R18 tires would be 50 front and 55 rear. Remember to check the PSI when the tires are cold.
We appreciate your business and thank you for choosing Michelin.
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The minimum recommended PSI for the LT275/65R18 tires would be 50 front and 55 rear. Remember to check the PSI when the tires are cold.
We appreciate your business and thank you for choosing Michelin.
The carry capacity vs PSI is pretty linear and you can do the simple math yourself
Best to have actually weighed your axle loading
For folks who want a PSI number and went to the OEM...note their verbiage 'Minimum recommended' is out of context if your axle load is not what they
used to develop that recommendation...
Made up this chart decades ago for a magazine article on LT vs P
class tires and how can two different sized tires have the same
max load ???
Note how linear the 'curve' is...that blip is from their typo info
provided to me for that article
Not surprising Michelin recommends a minimum 50 PSI. I have never seen a tire maker recommend anything less. Some people run less than 50 in their 'E' rated tires to achieve a smoother ride, but that is not recommended because of excess heat buildup due to underinflating.
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