OrngBalt

Ok guys... I have to start this off by saying I did not find this. A member on here sent me the link (Doc). I was asking about the change in the Speedometer and Odometer by changing the size of your wheels and tires.

http://www.dakota-truck.net/TIRECALC/tirecalc.html

Enter the tire sizes for both A and B on the left hand side. then click "Compare tire A to tire B"

Per the request and preference of some members I will also include the miata.net link

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

Both will give you a % that your speedo will be off. If you go smaller tires your speedo will read a higher speed and odometer will go up faster. Larger tires will be just the opposite.

Just thought they would be really useful sites so that you can have an idea of what the change is gonna be. Enjoy!

I wanted to add this section here because there seem to be alot of questions about larger wheel and lowering the car and if there is clearance. Many members have 19's and Sportlines. Members have gone as large as 225/35/20 and there are no clearance issues. You can use this calculator to see the differences in height of the tire. Because of the size of the tires you put on them 20's and 15"S are not really 5" different. Using the calculator LS stock wheels of 195/60/15 will only have a 2" difference from a 225/35/20! That means with the wheel gap of 3 or so inches we have, you could put the 20's on and still be able to drop the car an inch atleast.


Note**
Maybe someone can correct me on this but with HPTuners you can adjust the size of your wheel to the correct size and eliminate the difference.
For the 2.2's you cannot change your computer to adjust for size but using this site you can calculate which of the two stock sizes 195/60/15 or 205/55/16 is closer to the size you change to and see if it is worthwhile to have the dealer reflash you


Sticky Maybe?

BriantheLion26

This is a good one also.

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

It was helpful to me when I was searching for new tires.

OK that is a very nice site. + Rep

OrngBalt

Just thought I would give this a bump. I used it today, brought my car to the dealer to have my ECM changed (thanks to CED and Halfcent for finding out we can do this) I am changing from 3.5% off to .059%

BriantheLion26

Can any model do this? My speedo ran high to begin with (about 2 mph) so I put 225/45/18s on when I got new tires, I wanted wider ones anyhow, so it should be pretty close now, if not a lil too slow.

OrngBalt

I have no idea about changing the ecm on the other models for tire sizes. since the SS's all have the option of 17's or 18's you can switch between the two. I just know that the 2.2's either have 195/60/15 or 205/55/16. My new wheels were 205/50/16 so by switching the ECM to the 15" wheel size it changes my % of error.

OrngBalt

Bump for a hot topic as of late

Halfcent

I have used that Miata link for a couple of years now. That one was always my favorite.

DarkSergeant

^^AGREED! PLUS REP! The Miata calculator is awesome, even has a cool little diagram so you can see what you are putting on.

UmeNNis

errr a bit off topic but 235/40's will put more rubber on the ground than 225/45's correct?

oh and I like the second link better - easier! Although the first does have a lot of good info