Tire sizing

[Bryantclan]

We are buying an AllStar 3950 and have come across an interesting issue. We are replacing the front tires which are Michelin XRV 305/70R 22.5, which is kind of an odd size but for now we will stick with the tire that was spec’ed by the OEM till we understand the rig a little better. Now here is where the problem comes in, Michelins website says that tire (which is what is currently installed) needs to be on a 22.5 by 9.00 or 8.25 rim and according to Newmar the wheels are “Alcoa aluminum, 22.5 inches by 6.75 inches”. Am I missing something?

[Batman_777]

6 and 3/4 inch rim seems a wee bit small. The tire would look like a bicycle tire. 8.25 to 9" wheels would be normal.

["007"]

Why is it necessary to change the tires are they out of alignment and worn on outsides or damaged?
The Michelin's should last longer than your year of coach.
My 03 have 35000 miles and still are good no cracks and good wear.

[Mr_D]

Quote:

Originally Posted by Bryantclan We are buying an AllStar 3950 and have come across an interesting issue. We are replacing the front tires which are Michelin XRV 305/70R 22.5, which is kind of an odd size but for now we will stick with the tire that was spec’ed by the OEM till we understand the rig a little better. Now here is where the problem comes in, Michelins website says that tire (which is what is currently installed) needs to be on a 22.5 by 9.00 or 8.25 rim and according to Newmar the wheels are “Alcoa aluminum, 22.5 inches by 6.75 inches”. Am I missing something?

Last year I replaced the tires on our DSDP. I went to 305/70's on the front in order to use the full capacity of the 14,600# front axle. At that time I also replaced the 7.5 X 22.5 steel wheels with 8.25 Alcoa rims since I knew the old rims were the wrong width.
I question the width of the rims you say you have. I don't think Newmar would mount a tire on an unapproved size rim...but then again...maybe so. Is that from their literature, from the support people or direct from the rims themselves?
The 305 is only made by Michelin as far as I can determine. Continental lists it in their catalog but when I needed mine they weren't in production. Might be out there by now.
The 305 was made to satisfy a need on car carriers where the front axle is heavily loaded but there isn't room to mount a 290/80 tire.
If you're an FMCA member you should look at there Michelin discount member. But even if you're not a member it could save you far more than the cost of a one year membership.

[Bryantclan]

Quote:

Originally Posted by "007" Why is it necessary to change the tires are they out of alignment and worn on outsides or damaged? The Michelin's should last longer than your year of coach. My 03 have 35000 miles and still are good no cracks and good wear.

The front tires are past my personal comfort level, the back look new and have no surface creaks or other issues. All in all I would think I should have 3 or 4 more years on the tires based on age even with the current 61k miles, but the inspection showed otherwise.

[DBeauchamp]

I was in a tire shop on wednesday, vibration in the front at exactly 68mph... The shop took my front tires off and put them inside on the drive wheels after balancing (there was a bit of wear on the outside of the tires, toe-out). They also balanced front and aligned all the wheels on the coach. Very impressive the equipment, I was in the coach while it was done. No more vibration. While I was there, one guy made the comment that my 305/70's were mounted on the wrong size rims (8.25), he said they should be on 9" rims. The manufacturer sitcker states 8.25. Not a big difference, but wouldn't Newmar use the exact right size? But then again, who is right?

[Dav5942]

They should be the correct rims. My 4153 measure close to 10 inches(probably 9s). Have 65,000 miles on the five year old orginal 305s-hope to get 100,000.

[Mr_D]

Quote:

Originally Posted by DBeauchamp I was in a tire shop on wednesday, vibration in the front at exactly 68mph... The shop took my front tires off and put them inside on the drive wheels after balancing (there was a bit of wear on the outside of the tires, toe-out). They also balanced front and aligned all the wheels on the coach. Very impressive the equipment, I was in the coach while it was done. No more vibration. While I was there, one guy made the comment that my 305/70's were mounted on the wrong size rims (8.25), he said they should be on 9" rims. The manufacturer sitcker states 8.25. Not a big difference, but wouldn't Newmar use the exact right size? But then again, who is right?

The preferred rim width for Michelin tires is the first one stated in their literature, the second can also be used but it slightly reduces the weight rating. On the 305 I think it's about 500#'s at the maximum weight. You can verify the information by looking at Michelin's web site for their data.

[DBeauchamp]

Yep, thanks, found it, they state 9" as first choice, 8.25" as second choice. Wonder why Newmar would cut that corner, there would not be a huge diff in price between the two set-ups. Tire shop expert said if affects the durability of the line-up ring around the tire (part of the tire wall). Not going to worry about it.