I tried the tires and wheels place but didnt get a response so I'll try it here. I want to put 225/40/15 on and I know my speedo will be off, It will lower the car over a 1" and lower my overall gear ratio. Is there something Im overlooking or would handling be effected?

Thanks, Kosh

 

If your car uses a stock 205/60R15, that tire is going to be absolutely tiny. When your speedo reads 60, running those tires you will really be going around 53.7.

I find this calculator useful: http://www.miata.net/garage/tirecalc.html

 

arent 225's taller? he would be going faster than his speedo says

 

huh? i always thought that 225 was the width of the wheel

 

and you would be right. well, width of the tire, but i'm sure you meant that.

 

I have been running 225\50 15 for quite few years without a single problem; however the speedo is off by 5mph.

 

Be aware that the negative camber on the rears will make a low profile tire run mostly on the inside edge of the tread if you run too much air pressure.