Michelin Load & Inflation Tables

[mrkane]

Sleipnir's wheels are Firestone Accu-Forge part number 27471, 22.5x8.25, max cold pressure 120 psi, max load 7000 lbs.

The weight figures given above were taken after filling the fuel tank. I could watch the pricing at the local Flying-J from the campground, and went to get fuel without dumping the tanks when the cost hit a new low.

Weighing was an afterthought, as the coach was expected to be near the maximum load. I estimate both waste tanks were 90% full, fresh water 50%, LPG was 80%, and fuel was 100%. Dumping the tanks before travel is typical for me; therefore, I would expect the coach to lose ~1600 lbs, largely from the drives due to the location of those tanks. Diesel consumption is about 85 pounds per hour.

Recall my steer axle was less than 13,000 lbs actual weight at full loading, so the required pressure with the XZA2 Energy 295/80s is ~95 psi. At 23,000 lbs load, the drive also calls for 95 psi. The original placard calls for 12Rs at 105 psi steers, 85 psi for the rest.

I don't see how going to the 315s, but running at much higher pressures to limit dual spacing issues would result in a better ride?

I rechecked the GAWR and GVWR numbers to verify my earlier numbers are correct. My pick-up also has the sum of the axles greater than the vehicle GVWR: Front GAWR 4800lbs, Rear GAWR 6500lbs, GVWR 9900 lbs. The standard tires on the p/u are LRE, or 3415 lbs at 80 psi, so those ratings are not limited by the tires.

Bottom line is my coach is much lighter than later coaches, and the 295/80 in LRH are a good fit in terms of load capacity, dual spacing, and ride quality.

M.R.Kane
1987 PT40 'Sleipnir'
currently near Elmo, TX