semi-technical tire question
i currently have 275/55r20 tires on my 2010 suburban
can i put 275/60r20 tires on it.
what effect will it have and will it allign with the stock rim (alumin 5 spoke)
how will it affect the ride
can i put 275/60r20 tires on it.
what effect will it have and will it allign with the stock rim (alumin 5 spoke)
how will it affect the ride
Sidewall height is a function of tire width.
The difference in the sidewall height is 55 percent times the width of 275mm vs 65 percent of the width. So a 275 55 has a 5.95 inch sidewall while a 275 65 has a 7.03 inch sidewall. The factory 20's are 275 55 which is the 5.95 inch sidewall. and the whole assembly would be 20 + 5.95 + 5.95 = 31.9 inches. The sidewall math is 275mm width X .55 (55 percent) divided by 25.4 (mm/inch). I doubt that you can go more than the 55's and still have clearance. Gong to a 65 with the same width tire, your wheel and tire will increase by 1.08 inches all around (2.16 inches diameter)
My 2010 Suburban has the 265 70 17's which is a 7.30 inch sidewall. So my wheel and tire are 17 + 7.30 + 7.30 = 31.60 inches diameter and I don't have a lot of room left before I rub the front bumper. Maybe an inch in front of the front tire. I went round and round on this as I wanted to gain some ground clearance but I found that if I went to the 20's I had to trade off all of the gain in rim with shorter sidewalls for a net little or no gain - the wheel opening and steering ranges are the constraints.
A 275 60 20 will have a 6.49 inch sidewall and the assembly will be 20 + 6.49 + 6.49 = 33
And, it is not just the diameter in the front and back that will be a problem, you have to check to see if it rubs anywhere when turned lock to lock.
The taller sidewalls will generally ride better on rough surfaces.
Hope that helps explain it. I now know more about tire sizes than i really planned to.
The difference in the sidewall height is 55 percent times the width of 275mm vs 65 percent of the width. So a 275 55 has a 5.95 inch sidewall while a 275 65 has a 7.03 inch sidewall. The factory 20's are 275 55 which is the 5.95 inch sidewall. and the whole assembly would be 20 + 5.95 + 5.95 = 31.9 inches. The sidewall math is 275mm width X .55 (55 percent) divided by 25.4 (mm/inch). I doubt that you can go more than the 55's and still have clearance. Gong to a 65 with the same width tire, your wheel and tire will increase by 1.08 inches all around (2.16 inches diameter)
My 2010 Suburban has the 265 70 17's which is a 7.30 inch sidewall. So my wheel and tire are 17 + 7.30 + 7.30 = 31.60 inches diameter and I don't have a lot of room left before I rub the front bumper. Maybe an inch in front of the front tire. I went round and round on this as I wanted to gain some ground clearance but I found that if I went to the 20's I had to trade off all of the gain in rim with shorter sidewalls for a net little or no gain - the wheel opening and steering ranges are the constraints.
A 275 60 20 will have a 6.49 inch sidewall and the assembly will be 20 + 6.49 + 6.49 = 33
And, it is not just the diameter in the front and back that will be a problem, you have to check to see if it rubs anywhere when turned lock to lock.
The taller sidewalls will generally ride better on rough surfaces.
Hope that helps explain it. I now know more about tire sizes than i really planned to.
Last edited by JRacer; Oct 26, 2010 at 11:14 PM.
You will need a level kit and maybe some minor trimming (depending on wheel offset). I have 285/65/18s (32.6" diameter) with a 2.5" front and 1" rear level kit. I had to trim the front wheel wells by ~2 inches.
Yes, your ride should be slightly softer.
Yes, your ride should be slightly softer.
Similarly, I put a 2.5 inch front 1.25 inch rear lift/level kit on mine from "Truxx" to increase my ground clearance. Knocked the front bumper off it twice driving through cattle pastures. Once replace, once repair. Not fun.
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I wish only a heat gun was required in my case. At full lock and flex, it would have taken off the the front bottom valence bumper cap. I do take it offroad frequently so I needed to make sure there were no issues. To make 285/65/18s work on stock rims, I had to trim 2 inches of those valence caps.
I wish only a heat gun was required in my case. At full lock and flex, it would have taken off the the front bottom valence bumper cap. I do take it offroad frequently so I needed to make sure there were no issues. To make 285/65/18s work on stock rims, I had to trim 2 inches of those valence caps.






