Dale.Traveling wrote:goufgators wrote:zigzagrv wrote:
A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?
32', rear 85, front 90
Sunstar rigs are all built on a 18,000 GVWR chassis with a front axle rated at 7000 lbs and a rear at 12,000 lbs. No idea why the GVWR is derated by 1000 lbs. The tires size will be 245/70R 19.5.
Front axle pressures are way too high for the axle and can cause straight line handling problems. At that pressure you have a load capacity in the tires of 7780 pounds. Dropping to 80 PSI cold, the low limit of Goodyears chart, which still gives you a tire load capacity of 7280 pounds, 280 beyond the axle limit.
Same for the rear. 85 psi = 14060 capacity with a 12,000 pound axle. Drop to 80 psi cold also which will give you 13,666 pounds. Lot a wiggle room with tire capacity if weights getaway from you. I suspect you'll find the coach will be a lot easier to drive.
Couldn't agree more! We're thinking alike. I will be dropping the cold psi as you suggested. Even so, road and ambient temps in Fl will cause the pressure to rapidly increase from the cold settings. However, they will not as high as with my current settings. Aside: Had toe in adjusted by 1/16th yesterday and the short drive home seemed to have made a positive difference. But, it was a short drive and I'll not know until I drive it a longer distance. I do expect dropping the cold pressures will make the most noticeable difference. Thanks for your input!
Goodyear Inflation Tables (PDF)
