Tire pressure for underloaded main axle?

FlyingDiver · 10-02-2008, 12:57 PM

Not necessarily Spartan issue, but wasn't sure where to post this.

Newmar King Aire on Spartan K3 chassis with Michelin XZA1 315/80R22.5 main and tag. 20,000 lb limit on main axle, according to Newmar.

Looking at Michelin's chart for the XZA1 315/80R22.5, the lowest weight the list on the dual line is 11,680, which is over my limit of 10,000. It's way over the actual weight of 9300 (heaviest side). So I guess I just use the 85 psi for that weight. I'm assuming that's the minimum pressure they want in that tire. Is that right?

Seems a shame that I'm overbuilt on the tires for the main axle.

FWIW, heaviest side of my tag axle is 6690, which puts it just barely over the listed weight of 6670 @ 90 psi (single). I'll go with 95 on that axle anyway.

joe

FlyingDiver · 10-02-2008, 12:57 PM

Not necessarily Spartan issue, but wasn't sure where to post this.

Newmar King Aire on Spartan K3 chassis with Michelin XZA1 315/80R22.5 main and tag. 20,000 lb limit on main axle, according to Newmar.

Looking at Michelin's chart for the XZA1 315/80R22.5, the lowest weight the list on the dual line is 11,680, which is over my limit of 10,000. It's way over the actual weight of 9300 (heaviest side). So I guess I just use the 85 psi for that weight. I'm assuming that's the minimum pressure they want in that tire. Is that right?

Seems a shame that I'm overbuilt on the tires for the main axle.

FWIW, heaviest side of my tag axle is 6690, which puts it just barely over the listed weight of 6670 @ 90 psi (single). I'll go with 95 on that axle anyway.

joe

GaryKD · 10-02-2008, 04:20 PM

Hi Joe,
I agree with you. 85 PSI is what I would carry. Consider calling Michelin, just to confirm. Every time I have called them, they confirm 85 PSI is the lowest PSI they recommend.

FlyingDiver · 10-02-2008, 04:38 PM

I think I'll see what Spartan says before I bother calling Michelin. We'll be at Spartan on monday.

joe

racer0624 · 10-03-2008, 03:17 AM

Joe,
I've been told that any pressure less than 85#'s may allow the tire to roll off the rim when making slow, sharp turns. Our K-2 also calls for 85#'s on drive and tag.