Tire Sizing

[dyehardfan]

Greetings fellow forumista's. Yet another newb question for anyone with the know and the patience.

I have to put new tires on the '87 Spree rebuild and my lack of knowledge has come into play again. I am thinking of going 2.75" in the front and 3" in the rear. However, I'm kind of a heavy guy, 235lb, and am worried the 3" will rub in the rear. Probably going to replace the rear shock with something adjustable and wondering if this will help with tire/fender clearance issues.

Also, can someone help me with the metric conversions? What does an 80/90 convert to? What about a 90/90?

Thanks for any advice to be had.

[Wheelman-111]

Greetings:

The fender is fixed to the engine case. The shock won't change your clearance to the fender. Some have installed 3.00s on the rear of their Sprees, many reporting needing to address clearance issues. I'd stick to the known-to-fit 2.75 at both ends if I were you.

80mm divided by 25.4 per inch = 3.14". That would be the WIDTH.

In Tire-ese, 80/90 means the HEIGHT is 90 percent of the WIDTH.

90 Percent of 3.14 is about 2.83", so that's the HEIGHT.

Now you try! Plug the 90mm tire in there and see whatcha get. Don't forget to show your work.

[dyehardfan]

Awesome, thanks for the quick and easy to understand info. Cool. Thanks Wheelman.

So a 90/90 would be (90/25.4)= 3.54 * .9 = 3.19 which is too big. So a 80/90 is the biggest I would want to go if using a metric tire, no? The 2.75 and 3" in English is referring to tire HEIGHT, no? Just want to know as much as I can before I order the wrong thing.

Greetings:

The fender is fixed to the engine case. The shock won't change your clearance to the fender. Some have installed 3.00s on the rear of their Sprees, many reporting needing to address clearance issues. I'd stick to the known-to-fit 2.75 at both ends if I were you.

80mm divided by 25.4 per inch = 3.14". That would be the WIDTH.

In Tire-ese, 80/90 means the HEIGHT is 90 percent of the WIDTH.

90 Percent of 3.14 is about 2.83", so that's the HEIGHT.

Now you try! Plug the 90mm tire in there and see whatcha get. Don't forget to show your work.

[Rip_City_Spree]

I just put a 2.75 on the rear of my 87 spree with no issues