On my joe gibbs wheels i have 245-50s, back ones are getting a little worn, so im thinking about some 305s. Is there to much of a tire difference between the two? Im talking more on the lines of height, i know they will be wider, wood it look goofy or good? thanks

 

The 305's will bulge out too much on your 8.5" wide wheel and look funny IMO. I'd consider 285/50-20.

 

so the 285 would be the same height, just wider? because if i remember correctly, as an example, 285 would be the width, 50 would be the sidewall?

 

305/40/20 would almost be the same height

 

yeah, but i cant find any for sale, but one nitto, and i think they are discontinued, its a420 series i think. prolly will go with a 285 50

 

I made that exact same switch and the performance loss is very noticeable. The 305/50/20s weigh about 16 pounds more each than my 245/50/20s did. That's basically 60+ pounds of rotating mass I accumulating which transfers to ~200 pounds of stationary mass. With that said, my traction improved greatly which was a plus.

 

im still wanting the 245s in the front, just wanting a wide tire for the rear with the same overall diameter, what do u think about a 295-40? its pretty close

 

this will answer your height questions
http://www.miata.net/garage/tirecalc.html

 

another good answer for your wheel combo needs

4lo.com

 

245 is width in millimeters and the 50 is the sidewall to width ratio.