I have a 98 allegro bus 32' freightliner w/ 275 cummins.
I am having handling problems and trying to figure out the best tire pressure to run.
The sticker by the door says the tires are 19.5" but it actually has 245/75r22.5 toyo's
I found another chassis ID card with the documentation that says 235/80r 22.5 are the right right tire size, the original michelins were changed to toyo's, i had the MH weighed and here are the #s
front GAWR is 9350#s actual weight is 6620#s full fuel, water and propane
rear GAVR is 15500#s actual weight is 14300#s
The toyo tire inflation chart show the front tires should be inflated to only 70 psi and the rears to 95 psi, the rear seems ok to me but the front seems a little low and i don't feel comfortable running these tires at 70psi, it also seems that the front of the coach is a little light, could this be part of the reason for having handling problems ?
just looking for a little input from anyone that has had the same handling problems. cratch
Thanks Ken
* This post was
edited 05/21/12 04:07pm by badtip *
Your best bet would be to have individual wheel weights done after the coach is loaded for travel. If you can't do that, use the two axle weights you have and then refer to the tire inflation tables for the make of tires you have. If Toyo doesn't have something like that, try using the Michelin or Goodyear websites. Chances are the tires are overinflated for the load you have on them.
The weights i listed are within a couple hundred pounds of the actual weight that i go on the road with,
i have been running with 85 or 90 psi cold in the front tires and it seems that if there is no crosswind it drives JUST OK, if there is any cross wind at all it is a real challenge to stay in your own lane, i have had to stop and get my nerve up to keep going, i have had the front end aligned,i even had the steering box rebuilt, shocks are bilsteins and in good shape, tires are only 2 years old, the MH only has 31000 miles on it.
front GAWR is 9350#s actual weight is 6620#s full fuel, water and propane
rear GAVR is 15500#s actual weight is 14300#s
Your using axle weight, not corner weight, correct? So you front corner actual weight would be 3310 lbs per tire correct? And your rear corner actual weight would be 7,150 lbs per dual, correct. And you noticed that the dual psi is different than the single psi didn't you? I'm thinking your rear psi is quite high, but without seeing a chart, I'm only guessing. Can you provide a link to the tire chart that you are using?
Dont trust the lists from Toyo. They are made with old formula's wich come to mostly to high load capacity for a sertain pressure.
Better is to use a European chard for the same sise of tire and load-letter. They work with a saver power in the formula, and dont shift over for the load letters in the same list. For every load-letter ( F,G,H fi) a sepearate pressure/loadcapacity list is made)
But I once got hold of this European formula and went running with it.
Got much wiser when collecting information on the internet. My public map of skydrive/hotmail with 2nd from bottom easy spreadsheet to use
Look at my public map of skydrive, and search for the English maps between the Dutch.
If you want help, give me the details read from the sidewall of the tires, and I will calculate a save pressure for the tires, with no bumping. Reads something like this "maximum load single/dual xxxx lbs AT yyy psi/kPa ( cold) ". the Axle weights you already gave.
cratch 
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