Community Forums

RossB · 09-15-2015, 06:01 PM

On my coach I have 295/80r22.5 and if I change the size to 295/75r 22.5 will there be any problems other than the Speedo will be off a bit, I want to get away from the ridiculously priced Michelin tires, any suggestions of a good brand of a reasonable price

RossB
04 travel supreme
Dso4 400 hp

lllkrob · 09-15-2015, 06:06 PM

General S371 295/75R22.5 Tires

rhusak · 09-15-2015, 06:14 PM

Quote:

Originally Posted by RossB

On my coach I have 295/80r22.5 and if I change the size to 295/75r 22.5 will there be any problems other than the Speedo will be off a bit, I want to get away from the ridiculously priced Michelin tires, any suggestions of a good brand of a reasonable price

RossB
04 travel supreme
Dso4 400 hp

Ross..
Be aware the load capacities of 75 series is lower than the 80's. I have considered doing the same but really don't want to increase tire pressures injuring the ride.. But, they are cheaper..
Ron

Skip426 · 09-15-2015, 06:17 PM

Size is one thing, load carrying capacity is another .
Will the tire carry the weight of your coach , particularly the front axle?
Newmar had to recall my coach , when it was new, because the smaller front tire, installed at the factory, wouldn't handle the weight.
There were no heavier rated tires in the size so they had to go larger.

Some other members are reporting good results from their Toyos

Koop · 09-15-2015, 06:18 PM

You need to know your axle weight. The 295/80x22.5 has a higher load capacity than the 295/75x22.5 on the Toyo load and inflation chart ( the tires I'm running - which Alpine supplied as original equipment on my coach).

Gary RVRoamer · 09-15-2015, 06:53 PM

Ditto what the others said - the load capacity is the crucial thing.

But your reason for the size change seems off as well. Many excellent tire companies make the 295/80R22.5 size, so you don't have to buy Michelins. Or Goodyear either.

Consider Bridgestone, Yokohoma, Continental, Toyo, Dayton, etc. Bridgestone also makes the Firestone brand and they are usually a bit less expensive. Same for Michelin's BF Goodrich brand.

If you do not need the full carrying capacity of the 295/80R22.5 (e.g. on a rear axle or tag axle), you can substitute the 11R22.5. It is nearly identical in size where it counts, i.e. the rolling diameter. Will not affect the speedo or odo to any noticeable degree.

Rockbit · 09-15-2015, 10:29 PM

Going from 80's to 75's will decrease the tire height by about 2 inches. Not only will your speedometer be off, the shift points in the tranny will be off also. Before doing that, I'd check with Allison to see if they can write a program for the tranny to accommodate that change. Reprograming the speedometer and transmission could easily be in the several hundred dollars.

flynnwalter · 09-16-2015, 08:09 AM

RossB
You got good advice about weight capabilities of 75 versus 80 tires. 80 is bigger and carries more weight. I dislike Michelin, so I feel your pain. Do check with Allison, but I went up two tire sizes and 3.9" diameter and Allison said "no problem". Also, any truck/rv shop worth its salt will have software on a laptop they can plug into your computer port somewhere underneath the steering wheel, and with the new tires' revs per mile info the software changes your speedo/odometer with a click. Ours was done that way and it checked out using our gps. Should not be too expensive. You'll probably have to stick with the 80's after doing your research, but there are other good tires besides Michelin. We put on Bridgestone Ecopias and are very happy--but don't think they make the 80 series. I don't think I would put on tires that reduce my weight capability as our coach seems to get heavier each year for some unknown reason (smile).

Steve Ownby · 09-16-2015, 08:21 AM

Quote:

Originally Posted by flynnwalter

RossB
You got good advice about weight capabilities of 75 versus 80 tires. 80 is bigger and carries more weight. I dislike Michelin, so I feel your pain. Do check with Allison, but I went up two tire sizes and 3.9" diameter and Allison said "no problem". Also, any truck/rv shop worth its salt will have software on a laptop they can plug into your computer port somewhere underneath the steering wheel, and with the new tires' revs per mile info the software changes your speedo/odometer with a click. Ours was done that way and it checked out using our gps. Should not be too expensive. You'll probably have to stick with the 80's after doing your research, but there are other good tires besides Michelin. We put on Bridgestone Ecopias and are very happy--but don't think they make the 80 series. I don't think I would put on tires that reduce my weight capability as our coach seems to get heavier each year for some unknown reason (smile).

I believe Bridgestone has just started building the Ecopias in the 295/80R22.5 size. Previously the Bridgestone in that size was the R250, which is a good tire in its own right. The Ecopias, like Michelin's Energy is built for optimum rolling resistance.

Steve Ownby
Full time since '07

ChasA · 09-16-2015, 08:47 AM

I changed from 255R8022.5 Michelin to 10R22.5 Continental. My speedo was 3 mph off. I had Cummins Atlantic reprogram the computer for the new taller tires and now my speedo is dead on with a GPS.

Gary RVRoamer · 09-16-2015, 09:40 AM

There is no need to guess. Each tire manufacturer publishes detailed tire specs that include max load capacity (and the pressure required for it), and the tire revolutions per mile (which is what affects speedo & odo)

A typical 295/80 will turn about 503 rev/mile (each tire model or brand can vary a tiny bit). Anything within about 1% of that (plus/minus 5 revs/mile) won't change the speedo readings enough to worry about.