If I want to switch to 15" wheels, what size tires can I put on?

* Will Speedometer change?
* Do I need to go with 60 series tires on 15" (used 70 series on 14")

Right now am using 225/70/14's

 

rim size doesn't matter when going larger, but tire diameter is what you need to keep in mind. if you change the height it will affect your speedo...

Rim size going smaller you can hit your calipers / drums.... but same deal... its the tire's diameter that affects you...

 

Heres a little calculator that will help you gauge your speedometer with a tire change:

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

 

I switch from 14" to 15" all the time , I run a 205/75/14 snow tire , and a 235/60/15 inthe summer . I also have 17" rims with 245/45/17 that I run in the summer as well .

 

So a 15", just go with a 60 series?

 

Looks like 225/65/15 is way to go (speedo at 60mph, will really be 60.3mph)

 

yes .as long as you keep the over all diameter of the tire close to the original ,it is called plus sizing