Community Forums

Jzack · 12-02-2021, 10:20 AM

I need steer tires this spring and am contemplating upgrading my 255/70s to 275/70s. The main reason is it would move me to a J load rating from an H allowing me to run much less PSI. I've found out I have been running my tires a little low based on the charts. Once I add in a 5-10% cushion it would put me at 105-110psi on the rear and 110-115psi on the front. Dreading the expansion joints at those pressures!

Moving up to the J rated 275s would increase diameter 1.1" and lower my pressures down to the 85-95psi range.

Has anyone done this? If so, pros/cons, notice an improvement in ride?

Thanks in advance!

FIRE UP · 12-02-2021, 10:39 AM

Well,
Our coach, an '04 Itasca Horizon 36GD with the CAT C-7 330HP, was originally outfitted with Michelin 255 80R 22.5's. When it came time to replace them, due to premature cracking sidewalls and odd tire wear, not only was it a pain in the a... to locate those *proprietary* sized junk Michelins, but if and when I did find ANY, they were incredibly high priced.

So, with about an hours worth of research, I found that some 265 75's in the Yokohama brand, fit the bill just perfect. They ride nice, have been on the coach now for about 2.5 - 3 years or so and are looking great. Did this help you, not a clue. There's definitely lots of tire choices out there.
Scott

Jzack · 12-02-2021, 11:51 AM

Quote:

Originally Posted by FIRE UP

Well,
Our coach, an '04 Itasca Horizon 36GD with the CAT C-7 330HP, was originally outfitted with Michelin 255 80R 22.5's. When it came time to replace them, due to premature cracking sidewalls and odd tire wear, not only was it a pain in the a... to locate those *proprietary* sized junk Michelins, but if and when I did find ANY, they were incredibly high priced.

So, with about an hours worth of research, I found that some 265 75's in the Yokohama brand, fit the bill just perfect. They ride nice, have been on the coach now for about 2.5 - 3 years or so and are looking great. Did this help you, not a clue. There's definitely lots of tire choices out there.
Scott

Thanks for the reply. You found a very similar size for your application. Only a 1.3% difference. I bet that worked out good. I'm thinking the closest thing to my 255/70s is the 275/70s which is a 3% increase. Maybe there is something a little closer? I'll keep looking.

Crasher · 12-02-2021, 12:50 PM

Our 2003 Phaeton came with 235/80/22.5 Michelins. While carrying a 950# motorcycle on the back, the drive tires were overloaded. The 2005 models came with 275/80/22.5 tires. Long story short, Bob Tiffin agreed to pay half the cost for a new set of 275's of my choice. My tire dealer had a set of Goodyear 670's which he installed. The hardest part was getting them through the rear wheel wells and trimming the inner part of the well fiberglass for width clearance. It all worked and I ran them for five years and 50,000 miles. We had to reprogram the ECM for the different tire diameter, but in the end, I had more load capacity and "Maybe" a slightly better ride. Another benefit was Peace of Mind.

153stars · 12-02-2021, 01:30 PM

Quote:

Originally Posted by Jzack

Thanks for the reply. You found a very similar size for your application. Only a 1.3% difference. I bet that worked out good. I'm thinking the closest thing to my 255/70s is the 275/70s which is a 3% increase. Maybe there is something a little closer? I'll keep looking.

From what I've read 3% diameter is about max but I think more so at rear due to basically changing final drive ratio.

RealNiceTent · 12-02-2021, 02:08 PM

Jeff, do you know if Damon upgraded the tires in a sister model, or later(maybe earlier) year? IF they did then you probably won't have any problem. I doubt with just over a half inch increase in radius and width you would have any clearance issues. The biggest thing is will they dual up with enough clearance between the tires. If you won't have enough clearance between then you will have to replace the wheels.

wolfe10 · 12-02-2021, 02:11 PM

Assume that along with checking for clearance to suspension and body components, that you have verified that your wheels will accommodate the wider tires.

Jzack · 12-02-2021, 03:25 PM

Thanks all for the replies. I do plan on checking for clearance, I don't anticipate an issue but who knows. I checked on the rims and both tire sizes accommodate either 22.5 x 7.5 or the more common 22.5 x 8.25 so I should be good there.