So, the 17's use 275/40's while the 16's use 245/50's. Do they have the same overall diameter (i believe its 26")? Am i correct in thinking the 17's just have 1" less sidewall? If they don't, what size tires would i need to have the same dia. i did with the 16" rims?

I never could get a grasp on this tire sizing stuff.

 

Quick Lesson....

The P-Metric tire designation system....

P255/50-16 breaks down to-----

P- designates passenger car tire.

255- section width, in millimeters. this is measured at the widest part of the tire.

50-aspect ratio. the sidewall (in this case) is 50% of section width.

16-rim size.

To determine nominal tire diameter (unloaded) the formula goes like this

((section width * aspect ratio) * 2) /25.4 + rim size = nominal diameter.

Hope this helps.

 

Contact TireRack and check with them about tire sizes. I have changed tire sizes and always verify the sizes with them to make sure the speedometer is accurate. They have been right every time. Those plus/minus things people use to change tire sizes are not always accurate. They are pretty close but not always exact.

The 275/40's may not fit your car without rubbing. It depends on the offset of the rims you use. I just put a set of 275/40VR17's on a co-workers Trans Am, and let me tell you, those are some big tires!! He has a 97 Ram Air TA and it came stock with those tires, so everything fit. Have a good one.

Matt

 

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

Check this out, it'll let you compare 2 different sizes and give you all the relevant mesurements.

 

That's a cool link. I'll just have to bookmark it for future reference. Later.