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Old 05-14-2016, 05:22 PM   #1
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275/70/22.5 vs 275/80/22.5

I've got 275/70/22.5 Goodyear tires on our 40' DP, I have been seeing 275/80/22.5 tires on a lot of the new rigs. I am speculating the ride is much better with the 80 series sidewall. Has anyone done the swap? I don't think clearance would be an issue. What about minimum dual wheel spacing in the rear?

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Old 05-14-2016, 05:26 PM   #2
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I believe the "70" or "80" are the heights of the tires. It is the 275 vs 290 I would worry about for rear clearance.
I just bought a set of 275-8--22.5. My old ones aged out. They ride like a dream.

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Old 05-14-2016, 05:44 PM   #3
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Yes, the 70 and 80 are the aspect ratio, that # means the percentage of the width in sidewall height.

Anyone think it matters much if I do the fronts for now and the rears later? Would anyone make the switch for ride comfort alone if the existing tires are in good shape?
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Old 05-14-2016, 05:54 PM   #4
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The above link with give you the difference in tires.
1999 Trade Winds 7371 Cat 3126B w/current upgrades
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Old 05-14-2016, 07:20 PM   #5
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275/70/22.5 vs 275/80/22.5

I would ignore the mostly-wrong tire calculators on various websites and use the tire manufacturers' published specs to compare tires.

275/70R22.5, 265/75R22.5 and 255/80R22.5 are, functionally, the same diameter tire. They are all within a range of about 10 revolutions per mile. 275/80 is a larger tire and will affect the overall gearing and driving characteristics of the motorhome.

I changed from 255/80 to 275/70 and have no complaints.
2000 Holiday Rambler Endeavor 40PBD
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Old 05-15-2016, 08:42 AM   #6
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Use the tire manufacturer specs for dual spacing. That cannot be calculated with an generic tire compare tool - it's an engineering analysis. In all probability, though, those two sizes will be dual-spacing compatible if they are the same manufacturer.

The extra height of the 80's will increase the diameter slightly, which in turn reduces the rev/mile a tiny bit, but probably not enough to be concerned. Again, the revs/mile comparison will tell you the exact impact of the speedometer/odometer. The small amount of extra height should not be an issue in the wheel well either, unless it is already very tight there.

No problem changing fronts and rears at different times, as long as all tires on the same axle are the same.

Would anyone make the switch for ride comfort alone if the existing tires are in good shape?
Absolutely not. I sincerely doubt you will be able to tell the difference. A couple of psi more or less in the tires will have far more effect than a 0.10 difference in section height ratio. For a 275 width, we are talking only 1/10 of an inch!

Gary Brinck
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL
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