[Archived]

Art, you should get the coach weighed by axle. Then with the weight known you can go to the Michelin Pressure requirements/limits for the amount of weight the tire is capable of carrying.

I think you have the proverbial cart before the horse in your question.

[Chas]

Here is what is on the coach, Now the drive has 315-80R-22.5 Double Coin 22 ply 10,000 Lb single Duel 9090 new tires will be Toyos 20 ply 9090 single and 8270 duel way above spec

[Chip & Pam]

Art,

Try not to confuse the apples with the oranges.

First unless you can tell us which specific tires are on your coach we cannot tell you the tire rating. You can get that information right from the tire manufacturer’s web site and from the web site you will learn the rating is going to be as a single tire at a specific pressure with the maximum rating given at a pressure with lesser pressures having lower ratings. Additionally the manufacturer will provide different ratings if the tire is used in a dual set up.

That’s the apples part of the question.

The other part represented by the oranges is what the allowable weight per axle will be. That is determined by Prevost and in every instance it will be less than the tire’s maximum weight. For example you might have 315 tires on an axle rated for 14,000 pounds which means the tires should not ever see weights greater than 7000 pounds each.

But regardless of the fluff written above you have to weigh your coach, per axle and use the axle weights to determine the weight on each tire. Then you have to refer to the manufacturer’s tire pressure chart for your tire size to determine the pressure the tires will require based on the weight they carry.

Generally, (but based solely on the tire type) a 315 tire is likely to have a maximum weight rating of around 9000 pounds but as Will said what you really need to know is not what they are rated to carry, but how much are they actually carrying, and then how much pressure should be in the tires based on that weight.

[Archived]

Just to clarify a tire manufacturer might produce a variety of tires in a given size and depending on the particular model or type of tire it might have different weight ratings and different speed limits.

Within a given tire size a manufacturer might have a tire designed for a particular use such as a local bus application where the tire will have robust sidewalls to deal with frequent contact with curbs, and it may have a low speed limit such as 55 MPH. It might have a lower weight rating also.

But in the same size tire the manufacturer might have one rated for 75 MPH and have thinner sidewalls to dissipate the heat allowing the higher driving speeds. It may also have a weight rating higher than other tires of the same size.

[Roger]

Be sure and check the speed rating of any tire you are going to buy.

The last Toyos I had on my coach were only rated for 65.

If you only drive 65 then no problem but exceeding the rated speed limit and/or driving at the rated speed on a continual basis is not for me. I want a little safety margin below the rating.

[Dick]

I had never had my coach weighed, but we were at a CG where a guy was there for a rally. When he finished weighing each of my tire/sets, there really were not many surprises, except the steering tires….Found the coach is so heavy on the front, it required maximum pressure for the front tires–130PSI. These are relatively new Michelins

There are some places I might reduce some miscellaneous weight, but the front sure isn’t one of them.

At any rate, I run 130 now that I’ve been shown the actual weight up front. It’s the way Marathon built it…Not much I know to do other than that.

[Archived]

That’s exactly the reason I changed mine to 365’s, I had the same issue, tires at max pressure due to steer axle weight. Went from 125 psi to 105. I can just imagine the pressures on a hot summer interstate day running maximum pressure cold.

[Kirby]

I did as Tom – our front is heavy and I had to run 130 psi on the 315’s. Changing to 365’s allowed me to run 105 – much nicer ride… and have an extra margin in weight rating.

There’s a lot of talk about hard to get 365’s or “I wouldn’t re-engineer my bus….” but, if I have to wait a few days to get a new tire so be it. The bennifit’s outweigh that *potential* cost. And Prevost started started shipping with 365’s so I figure they felt the buse’s needed it.

I really want to look into Lithium and Super singles to shed more weight. These Marathons are heavy!