Tire Pressures

John34 · 12-17-2008, 07:34 AM

I'm looking for help with tire pressure in my 2009 4333 Newmar Ventana. I have 305/70R 22.5 Michelins. The data sheet behind the drivers chair from Newmar says.Cold psi- Front axle,single wheel 115. Drive axle,dual wheel 85 psi. Rear tag axle,single wheel 75 psi. The front axles is rated 14,000 GVW , Drive is rated 20,000 GVW. The tag is rated 10,000. I have max Gvwr 44,000 and GCWR 54,000. I'm fully loaded and went across a CAT scale at Loves. The results said my front axle is 11920 and the rear (tag and drive combined) was 22760. Now I know each corner would be better,but this is all I have for now. The coach had 110 in the front and 85 in the drive and 75 in the tag when I got it. I thought that was to low and went 110 all around. Looking for some idea where I should be.

John34 · 12-17-2008, 07:34 AM

I'm looking for help with tire pressure in my 2009 4333 Newmar Ventana. I have 305/70R 22.5 Michelins. The data sheet behind the drivers chair from Newmar says.Cold psi- Front axle,single wheel 115. Drive axle,dual wheel 85 psi. Rear tag axle,single wheel 75 psi. The front axles is rated 14,000 GVW , Drive is rated 20,000 GVW. The tag is rated 10,000. I have max Gvwr 44,000 and GCWR 54,000. I'm fully loaded and went across a CAT scale at Loves. The results said my front axle is 11920 and the rear (tag and drive combined) was 22760. Now I know each corner would be better,but this is all I have for now. The coach had 110 in the front and 85 in the drive and 75 in the tag when I got it. I thought that was to low and went 110 all around. Looking for some idea where I should be.

Spikester · 12-17-2008, 09:16 AM

You should have a Michelin Tire Brochure included in with all your operators/equipment manuals that they gave when you bought our RV. This brochure will give you the correct tire PSI for the actual weight being carried by your various axles. You will need to know the model, and the load range of your tires.

If you cannot find your brochure he is a link to the Michelin RV Tire Website, select the model of tire you have, it take you to a page that allows you to download a PDF file with the info you are looking for.

Spike

**Route 66** · 12-17-2008, 09:59 AM

HERE is a link to the load table.

At 11920# on the front, the table lists 90 psi for an axle load of 12440#, but that is assuming each tire carries 6220# equally.

110 psi in the front is probably more than you need, but not knowing the individual wheel weights, that is the safest way to go, although you will get a harsher ride.

85 psi in the rear tires will carry 21060# which more than adequate for a 20000# rear axle.

85 psi in the tag axle will carry 11880#, also more than adequate.

I'm quite sure that 85 psi in the rear and tag is adequate.

I'd leave the front psi as is until you can get individual wheel weights, and I'd lower the rear and tag to improve the ride.