Could someone please tell me which size tire will yield a taller side wall on a 20x10.5 rim? Is it 275/30/20 or 255/35/20? With the 275/30/20 tire, the sidewall will be 82.5 mm, whereas the 255/35/20 will be 89.25. But since the 255/35/20 is stretched on a 10.5" wheel, will it be shorter, about the same, or still taller than the 275/30/20 tire?

 

The diameter won't change much w/ a 255 stretched on a 10.5, if you were talking something really stretched like a 225 on that wheel then yes, rolling diameter would be affected but the 255 on the 10.5 won't change much at all, it'll still be around a 1/2" taller (outside diameter) than the 275.

 

Thanks for your reply, blnewt. I think the sidewall difference between the 255/35 and 275/30 tires is only 6.75mm (89.25mm - 82.5mm), which is around 0.266", or roughly 1/4". I don't think the difference is as big as 1/2" like you said. Is that correct?

I'm wondering whether I should pick one size over the other. I'm not sure whether either size has clear performance advantages over the other, if you know what I mean.

 

255/35R20 all around and my rear wheels are 10.5"

 

The sidewall is about a 1/4" taller, that makes the overall height (or diameter) of the tire a 1/2" taller. If you look at the tire and visualize adding a 1/4" to the top of the tire and a 1/4" to the bottom it should become clear, or maybe it was just a misunderstanding of what measurement was being talked about

And Ryne's coupe is a great example of what a light stretch does to the rolling diameter, very minimal effect.

 

Nice.. So if I run a 20x10 front 20x10.5 rear and use the same 255/35 size tire on both, my rolling diameter should still be good for my AWD then? I was concerned too about the stretch on the 10.5 affecting the rolling diameter

 

You will DEFINITELY be ok. I have 255/35R20 tires all around and my front wheels are 9", while my rears are 10.5". No issues with AWD and I have had them on for several months now. It's a great route for us AWD guys to go to play it safe and keep things simple.