Help with understanding a tire inflation chart....

[bwze]

I'm looking at the tire inflation chart below from Bridgestone trying to decide what the tire pressures should be for my 11R22.5's on my 4106. I'm weighing in at 9620# on the front, which estimates around 4810# per wheel and 16420# on the rear duals, which estimates around 4105# per wheel. Should I translate this chart to mean 75 to 80# on the fronts and 70# on the rears?

[bevans6]

Yep, exactly right.  Big file warning if you are on a metered service - don't load it unless you want it!

Your duals are loaded under the lowest load on the chart, so 70 psi is correct.  Your single fronts are loaded under the 80 psi load, but over the 75 psi load, so 80 psi is correct.

Brian

[lostagain]

Yes.  That is the pressure I run on the Courier 96. I use about 80 psi with the 5C. Anything more will give a harsh ride.

JC

[bwze]

Thanks guys, just needed a second set of eyes. I really appreciate your help.

Brian, I modified the original post to circumvent the download issue, thanks for making that comment.....didn't even think about others on metered services.

[belfert]

If you didn't have full tanks, cargo, passengers, and such when weighing I would go 10 to 15 PSI higher than the PSI required for the as weighed weight.

[goutoe]

Thanks for posting the chart according to that I am over inflating my 12r22.5s I am anxious to adjust the pressure and see if it smooths out the ride. John

[lostagain]

To the few newbies that have joined here lately, if you didn't know: don't run your tires at 100 psi just because the tire shop inflated them that much and told you all truck tires get 100 psi. They are the same guys that overtorque your wheel nuts with their 1" air gun. Weigh your bus for each axle,and look up the tire manufacturer's inflation charts according to your axle weight.

JC

[Ed Hackenbruch]

And on the other hand,... the lower the tire pressure, the more rolling resistance you will have, which means more heat in the tire and lower fuel mileage. Everything is a trade off.

[HB of CJ]

Like for the right front side and the rear left side and etc.?  Not that it would make that much difference as far as tire inflation goes, but it might give you an exact idea how well balanced the coach is at full load curb weight with the entire nine yards including your rotund mother in law.

FWIW, for high speed hot running like in the summer in the desert, (yikes!) sometimes high tire temps relate ALSO to under inflation especially with the rear duels, or with one rear tire being way low in comparision to the other three. Maybe a little bit more air?   HB of CJ (old coot)

[Kevinmc5]

Great question bwze. This is why I love this site. I have been ruining 100psi in my tires on my PD4106-2471 because the P.O. did. Had know idea to even think of that question. Just got all new bridgestone tires for mine. The tires that where on it are still very good but are 10 years old. Can't Waite to feel the difference the air psi will make.

Thanks Kevin

P.S. The person who got me the tires told me prices on bridgestone tires are going up 14% in April. If there going up you can bet the rest are

[RJ]

Billy -

Unless you ran your coach over the scales in "ready to roll" condition, you might want to add about 200# to each tire's weight.

When I did that to your numbers, reviewed the chart, and included the all-important empirical fudge factor, I come up with 85 psi front, 75 psi duals.

And, just so you don't have anything else to worry about, mull this over: You've got 64% of your weight on the rear axle - more, percentage-wise, than a 911 Porsche!  (NOW you see why the 4106 is considered the first generation "Sports Car of Buses?")


Kevin -

Before you start playing with tire pressures, be sure to run your coach over a set of truck scales to get fairly accurate weights on each axle.  Otherwise it's like trying to shoot an arrow backwards.

FWIW & HTH. . .