off road tyre sizes explained

Post by **Hacksawbob** » 18 Jan 2006, 14:58

How come, you get the normal 205/80/R14 size which I understand, and then you get 35x11.5 r16 what does that all mean?

Post by **Diamond Hell** » 18 Jan 2006, 15:03

I wouldn't waste too much time worrying about it, Bob - you can either have 15" wheels and tyres up to 225/75 or 16" wheels and lower profile tyres.

I suspect they're imperial measurements, like cross-ply tyre measurements from way back, when off road tyres were available in 6.50 or 7.50 R15 or R16.

*leans on gatepost, chews straw*

Post by **toomanytoys** » 18 Jan 2006, 17:36

They be imperial.. did you get it from an American site by the way? or American made tyres?

Post by **Hacksawbob** » 18 Jan 2006, 17:56

just curious I know they wont fit just craving knowledge. Clive'll know, Too many, I've seen these a lot over here on Ebay
say like
this

Anonymous · Post by **Anonymous** » 18 Jan 2006, 21:02

"Old" tyre dimensions are in inches, e.g. 7.50 x 16. The tyre carcass width and height are both 7.5", so there is no need to specifiy an aspect ratio (it is 1.0), and the overall tyre diameter is 2 x 7.5 + 16 = 31", in this case. The most common Jeep / Land Rover tyres were from 6.00 x 16 to 7.50 x 16, although some went up to 9.00 x 16. (A 7.50R16 tyre is just the radial-construction equivalent of a 7.50 x 16.)

Newer tyre dimensions are a mixture of metric and imperial quantities, e.g. 245/80 x 16, indicates a tyre carcass width of 245mm, an aspect ratio of 0.8 or 80% and a wheel rim diameter of 16"! A change became necessary when tyre technology enabled aspect ratios of less than 1.0. Low aspect ratio tyres give better on-road handling, all other things being equal, but there is still a place for the trusty 7.50 x 16 on 4WDs.

MG