SORRY for the post but I never took autoshop. I can't seems to find a decent used 195/75/14 in this town but there is a good 185/75/14. Seeing as how I'm already driving around on the donut at 55mph I'm wondering if it's not a big deal to just replace my flat/donut with the 185mm wide tire, to save a couple of bucks (new tires are expensive). Also I'm wondering why the donut says "Not to exceed 50mph (100km/hr)?" Last I checked 100kmh was 62 mph.

THANKS TEAM

I would add that your donut is probably at least 20 years old. I don't think it's safe at all to drive it around at speed, unless you don't mind risking a high speed tire failure. You might try tirerack.com. They have a good selection of tires and are reasonable. At the very least, if you buy used tires, get two in a size that match on the same axle. Don't volunteer to be a candidate for the Darwin award.

the donut should also say do not exceed 50 miles. they wear out quick.

get 2 tires the same size. 2 different widths mean 2 different diameters and rear ends don't like 2 different speeds. the 185 will turn faster than the 195 and burn it up. good luck, chuck.

I am skeptical that "two different widths means two different diameters," considering they themselves are two different dimensions - but if you're right you're right, i'm not gonna measure 'em. Looks like i'm headed to America's Tires today after all...

They are absolutely different diameters.
and as Porkface said, the Spider gears in the Differential will be working way to hard all the time.
http://www.dakota-truck.net/TIRECALC/tirecalc.html
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/

Find out for yourself.

http://www.miata.net/garage/tirecalc.html

Dan

No don't do it, tires and brakes are the most important parts on your car, don't skimp on safety.

Also the donut is a temporary tire designed to be driven a few miles until you get a flat fixed. The rims are different sizes.
Dan