So say i put on 19" wheels... that would be around 1/2 inch in increased clearance...then put on Eibachs that lower it 3/4 inch....so in reality i only dropped 1/4 inch in ground clearance....right ?


Have a sloped driveway...kinda important to figure this out.

Mike

 

its pretty important that with the 19" rims you go with a smaller sidewall, leaving the overall diameter of the tire the same. otherwise your gearing will be off, and not in the "better for gearing" way. actually worse(tho top speed would be higher assuming there is a limiter)

so with the same overall diameter, the clearance is not affected in any way. and with the drop it would be 3/4" lower.

 

I put on the Pro-Kit with 19" rims 245/35/19 on the front and 275/35/19 on the back , as of right now the measurements are as follows

Front : 26" from the pavement to the top of the wheel well

Back: 26 1/4 " from the pavement to the top of the wheel well

I have them installed around May of this year.

Now those tires I choose gave me the same profile as stock then I put on the Eibachs.

 

yeah, what ares said.

personally, i am surprised that people want to lower their cars. i have a hard time making it over some bumps and parking structures as it is. that is just me though.

oh, the only way i can think of that you could get a 19" rim without following the +1 or +2 sizing formula and not mess up the speedo is to get something like that hypertech (is that what it is called?) computer thingy. suppossedly you punch in the information of your new tire setup and it will recalibrate your speedo. you can also calibrate other things like rev limiter, ignition timing. not sure if they make it for the z yet. i know it is out for the mustang and camaro.

 

If done properly, it does not matter if you are getting a 17,18, or 19 inch wheel because the outside diameter of yout tire should be within 3% maximum of your stock tires. I would strongly suggest you keep it under 2%. You can use the website to determine your stock diameter wheels and then type in different tire sizes for what you might put on as a mod.

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

If you go over or under 3% outside diameter, then your ABS braking system will not work properly, you speedometer will be off (that webpage shows you how much it will be off), and the VDC feature might cause your Z to actually cut your throttle off or brake certain wheels. You might ask why? It is because for example if you put on lets say smaller rear tires (outside rolling diameter), then the car knows the rear wheels are spinning faster than the front and since it is programed to not let slipping to occur, braking or loss of power occurs.

Thus, the wheel gap on an 19 vs 17" tire should be equal because if done right, the rolling diameter is the same.