Tire Size Question

read & learn · 03-22-2011, 04:00 PM

Can I replace my Michelin 275/70 R 22.5 with 275/80 R 22.5 on my 2005 Kountry Star 3910

**"007"** · 03-22-2011, 04:23 PM

Here is a thread on tires and tire replacements & tire sizes. There a links within the thread.
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GaryKD · 03-22-2011, 04:33 PM

Hi read & learn,
Are you replacing tires? If so why? We have the same coach. I have 69K miles and my tires look like new. Right now, I have no plans to replace them until the coach hits the 10 year mark.

I am within 1K of GVWR and the 275/70s are performing perfectly. The ride remains very smooth.

To answer your question, some time ago I went to the Michelin site and got the dimensions of both tires. The bottom line is the steer would be difficult when going to full cramp. The rear would be too close for me on spacing. Could it be done, yes. I would not be comfortable with the setup.

read & learn · 03-23-2011, 05:23 AM

Hi Gary
As we are getting ready to return to the factory yesterday, I noticed cracks in the side walls of one of the tires while during my Pre-trip check. The cracks are not the small little cracks at the printed area, but runs about 3" long between the rim and bottom of tire, plus a couple of smaller ones
Is it safe to drive, if you go by what Michelin says it would be OK. The Wife says NO it is time to replace our 7+ year old tires. They were stamped week 07-year 04, that tells me they were over a year old when my coach was built, Born date May 15, 2205.
Reason for size change was Tire Dealer has back order on 275/70 R 22.5 tires ,but could put me in 275/80 R 22.5 right away.
Waiting for call if he can locate 6 new 275/70 R 22.5> I was just looking at my option.
We have just over 40,000 miles on them and they look like new except for the new cracks.
Thanks for the response.
Joe

**Route 66** · 03-23-2011, 05:39 AM

As Gary notes, some Newmars will have front tire clearance problems with larger tires when turning and the dual spacing is an important issue.

soricobob · 03-23-2011, 06:29 AM

Have you determined why the cracks have appeared? On my tires I have similar cracks which I noticed, and can only surmise that I should have parked on plywood over the concrete.

thelastplace · 03-23-2011, 06:42 AM

Keep in mind that an '80' tire is taller than a '70' tire. You aren't just changing tires, but all the relationships between your tire and the road. That number is a % factor of tire height to width. A 70 x 275mm is 192.5mm high. An 80 x 275mm is 220mm high. That may not seem like much, but it could effect speed readings, MPG, handling and, as mentioned above, wheel clearance. The tire dealer should know better, he just wants to sell tires.

But the true travelers are they who leave for leaving’s sake
Saying continuously, without knowing why: ‘Let us go on’.
Paraphrased from Baudelaire’s ‘The Journey’

Perry White · 03-23-2011, 07:51 AM

All the time you are running on the highway, you are going to be thinking about your tires. Replace them for piece of mind. If something does happen, your better half now has a told- ya-so