Im using this site (http://www.miata.net/garage/tirecalc.html) to get an idea of the difference in size when changing the tires on my 07 Sahara Unlimited from the stock P255/70R18 tires to either the new BF Goodrich Mud-Terrain T/A KM2 or the Mickey Thompson Baja MTZ Radials. Problem I'm having is that 35x12.50R18/D is the size that BFG gives on their site, and Mickey Thompson gives LT325/65R18. How do I convert the 35x12.50R18/D to be able to enter the proper numbers into the chart on the site mentioned above?

Also, I have been hearing/reading about backspacing. What exactly is that? I am hoping to get the 4" TeraFlex suspension lift kit and one or the other of the 35s mentioned above, am I going to have to anything extra given that I will be using my stock 18" rims?

Thanks!

 

Captian

35x12.50x18 should be converted to a 325x65xr18 Remember these tires will not be 35 exactly I have the the procomp x terrians and they messure up to 34.6. Now i am not a 100 % sure about back spacing but many people have told me between 4in and 4.5 in backspacing you should be fine. maybe someone can back me up on that.

 

The nearest metric equivalent to 35x12.5R18 is 315/65/18. I think you'll find this link to be very helpful.

As far as backspacing, I don't recall what's required to clear 35" tires, but the 4" lift should easily provide enough height that you don't encounter any rubbing... however, I'm not sure how far you'll have to offset the tires from their mounting point (which is what backspacing means). Good luck!

 

thanks so much for that write up, i now understand backspacing!