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Old 08-23-2020, 12:28 AM   #1
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Larger Tires

I have a Full-timer with a Thor Challenger 37GT that I LOVE. It has taken us on an 8,000 mile journey across America with little trouble. We replaced the front tires with slightly larger tires (245/75/22.5 vs 235/80/22.5) and I could definitely feel an improvement in handling side winds and tracking. My rears are original 7yr old Micheliní 235/80/22.5 with 40,000 miles and still look great with virtually no visible dry rot and plenty of tread but I feel like itís time to replace. I am contemplating a 255/70/22.5 for the four rear tires. I am sure they will fit properly on the 7.50 rims with No clearance Issues but kinda concerned about the pros and cons. Any thoughts?
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Old 08-23-2020, 12:32 AM   #2
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If the lower profile of the new tires keeps them about the same diameter as the OEM tires: go for it!
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Old 08-23-2020, 01:36 AM   #3
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You will have about 1/2 inch less space between the rear duals at the widest part of the tires

Check your clearance now and if there is plenty of room as Bob noted go for it
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Old 08-23-2020, 09:31 PM   #4
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The 235 and 255 are close, diameter 235 is 37.1 inch, 255 is 36.7 Speedometer error at 60 is 1.1 mph. Dual wheel spacing the 235/80 needs 10.3 inches the 255/70, 11.6inches (check your rim offset)

Tire calculator here: https://tiresize.com/calculator/
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Old 08-23-2020, 10:11 PM   #5
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Originally Posted by lwmcguir View Post
You will have about 1/2 inch less space between the rear duals at the widest part of the tires

Check your clearance now and if there is plenty of room as Bob noted go for it
Yep, if your rear tires touch tires, you won't go very far The mm number is the section width at max inflation pressure. Lower pressures will increase the section width. Just saying be careful.
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Old 08-24-2020, 02:06 AM   #6
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Probably not a problem but-
You can check dual wheel spacing by looking up your rims offset, this is the HDS (Half of the Dual spacing) or measure the distance between the center grooves on your present tires.
My 22.5x7.5 rims offset was 6.44 inches, dual spacing was 12.88 inches
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