new tires

[Tim Bookmiller]

I had new 315/80 r/22,5 tires installed on my 4106 conversion and the tire shop aired the front to 110 lbs and the rears to 100 lbs seems high to me and a rough ride what do other people run for tire pressure ?

[DoubleEagle]

Go by what the coach manufacturer recommends first, it might be on a plate in the coach or in an operators manual. If you don't have that info, I am sure the other 4106 owners will chime in soon. On my Model 10 Eagle, the factory plate states 105 psi for the front, and 90 psi for the rears and bogies. The pressure used is a balance between steering stability, load capacity, fuel mileage, and ride comfort.

[Geoff]

I have a 2 axle RTS with the same tires and I only put 90# in the front tires, 100# in the rears.  Rides better that way, and don't worry about anyone telling you about higher tire wear with lower pressure tires-- you are never going to wear those new tires out.

--Geoff

[DoubleEagle]

I have a 2 axle RTS with the same tires and I only put 90# in the front tires, 100# in the rears.  Rides better that way, and don't worry about anyone telling you about higher tire wear with lower pressure tires-- you are never going to wear those new tires out.

--Geoff

Good point, age will kill most of our tires first, but keep the load capacity of the tire up to the weight it is carrying.

[Tim Bookmiller]

I will check 4106 owners manual but I am thinking I ran 85-90 lbs on front tires and they were knee deep in rubber tread just age sidewall cracks before replacement Thanks for all the responses

[lostagain]

Weigh your bus by axle. Then go to the tire manufacturer's site. It will show the pressure according to the weight. I run 80 lbs all around.

JC

[Dave5Cs]

My 5C weighs 28,568 lbs. Toyo tire chart for 11R x 22.5 says for axle weight I have front 85 and the rear is 80. Rides smooth.
Dave5Cs

[lostagain]

Dave you are heavy! Must be the cats...

JC

[luvrbus]

That is a big tire for a 4104 (like huge), you better go by the tire manufacture to low of a pressure will kill a 315/80x 22.5 BTDT

[gumpy]

Low air pressure (i.e. that recommended by the manufacturer for the axle weight) can cause the tires to cup on the outside edge. Once they start it just gets worse.

I ran mfg recommendation on mine. Cupped the steer tires in about 30K. Now I run 100-105 in them and have not had any problems. Same model tire as before, just more air.

[Dave5Cs]

JC its the gold faucets and tub the Saudi's left in it. and I was in it when I had it weighed.  

JC what does yours weigh you have me wondering now...

[luvrbus]

Low air pressure (i.e. that recommended by the manufacturer for the axle weight) can cause the tires to cup on the outside edge. Once they start it just gets worse.

I ran mfg recommendation on mine. Cupped the steer tires in about 30K. Now I run 100-105 in them and have not had any problems. Same model tire as before, just more air.

Same here I pay no attention to weight vs air pressure after a set of Michelin cupped on me 

[lostagain]

Never had a problem with cupping.

Dave, we don't weigh much less than you. 27000.

JC

[RJ]

Tim -

I agree with JC about weighing the coach first (in "ready-to-roll" trim), then adjusting the tire pressure based on the tire manufacturer's chart for the weight.

Tortoise weighed in at 27,275 when I ran it across the scales, which, for my 12R22.5s, equaled 80 psi front & rear.  I added a "fudge factor" and used 85 psi, and the coach rides much better than the 100 psi all around that was used previously.  Have noticed no front tire cupping in 18,000 miles so far.

The 4106 I owned wasn't much more than a shell - 6 bunks and 8 seat band bus - and it weighed 20,687.  That translated to 65 psi all around, which I felt uncomfortable with, so used 75 psi.  Rode fine.

As Clifford said, a 315/80R22.5 is a really big tire on your coach.  Was that the closest size they had to 495 revs/mile?

Walter -

No tire pressure data was ever published for the 4106 by GMC, nor any GVWR, either.  Had to use the fed's bridge axle weight limits as a guide to GVW - 12K front, 20K rear for 32K total.

JC & Dave

Looks like Tortoise is right in the ballpark.  I agree with you, JC - the cats are definitely what sends Dave's over the 28K mark!   

FWIW & HTH. . .

[Lin]

I do the same as RJ-- take the tire manufactures recommendation and add 5 pounds.  No problems that I have noticed.

Geoff-- Considering the rear has duels, usually the front pressure is a drop more than the rear.  What made you reverse the commonly used formula?