I have 275/35/r18 in the back and they are a smaller size than the ones in the front. Smaller I mean the sidewall is smaller than the front thats how they came from wheels next and I know another member that has this. Its time for new rears and I want either the same size or bigger for the back which number would I go.... 265?

 

Well, not entirely sure what you are asking. If you want a wider tire, then you'd want 275 to get bigger... ie 285 etc...based on the limit of your rim. If you want a taller tire, then 35 would have to get bigger, ie 40, 45 etc...but be careful with this as it will change how far your speedometer is off and also can affect abs. Hope this answers your question.

 

 

I want a taller sidewall sorry for the confusion. I guess a 275/40 or 45 will work. I dont want to go too big I guess I need to go to see what the fronts are.

 

275/40 is the normal upgrade for 18 inch wheels

 

Yeah, tpically people will go with 18" rims all around. The fronts will be 8.5" wide and a 245R40-18 fits great. The rears tend to be a 9.5" wide rim with 275R40-18. There are several tire calculators out there....I know this is a common one used: http://www.miata.net/garage/tirecalc.html

According to that calculator, if your stock was a 235R50-17 (like mine) then a 265R40-18 is only 0.4% off. Play around with it and see what you come up with!