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Topic: 1989 GV tire pressures? (Read 362 times) previous topic - next topic

1989 GV tire pressures?

First of all, let me state what it says on the placard on the wall next to the driver's elbow: 80 PSI for singles and 70 PSI for duals.
Then it also says tires: 9Rx22.5
Front axle capacity: 7,500#
Rear axle capacity: 13,500#
Our coach is the Oshkosh Truck leaf spring version, NO air suspension.
OK, we got that stated. Does this mean FOT stated specs for tire pressure should be followed? They did build the coach and one would think they would be the deciding factor.
Now, here is what we have for tires: Michelin 235x80x22.5
Does this change the PSI I should inflate the tires to? Keep in mind that our 1989 36' GV does NOT have a lot of carrying capacity/storage for "lots of stuff". None of the compartments are filled to capacity with anything heavy. I personally could carry everything in any compartment in my arms with no problem.
When we first got the coach the front tires were reading 100 PSI and the rear duals were reading 90 PSI.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: 1989 GV tire pressures?

Reply #1 –
Go to Michelin's Inflation Table for your new 235/80R22.5.  Look up for your actual weight or, if you don't have that, for the weight on the GVWR sticker.  That will show you the minimum PSI for that weight.  Add 5-10 percent to the minimum.

Assuming you have 6.75" rims, the Michelin 255/80R22.5 is a common upgrade from the 9R22.5, at least on the U225 and U240 which also came with the 9R22.5 tires.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 1989 GV tire pressures?

Reply #2 –
YUK!!  (To be polite)
Seems like 80 PSI on the fronts and 85 PSI on the rear duals from what I can glean from the chart.
Just the reverse from what FOT specs on the plaque. They have the duals inflated 5 PSI lower than the singles and that makes sense.
So here we go again!! No strong definitive answer I can use!!
Like horseshoes--just get close.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD
 

Re: 1989 GV tire pressures?

Reply #3 –
I'm a few thou over you at about 8500 front.  I went back to 9R tires and it likes 88 -90 front and 82-85 ish rear.  From my tire chart..
 I really like the tires also .