Wheel sizing info.

[Southern Boy]

I think I read a thread somewhere in here about the effects of putting larger wheels on the car.

I think the thread said it was alright to go one inch larger that stock, but any wheels more than one inch over stock could cause problems with shifting and the indicated speed and the odometer.

I’ve done several searches to no avail to obtain the information.

If anyone has this information or can point me in the right direction I would be greatly appreciative

 

[scottdk]

I think I read a thread somewhere in here about the effects of putting larger wheels on the car.

I think the thread said it was alright to go one inch larger that stock, but any wheels more than one inch over stock could cause problems with shifting and the indicated speed and the odometer.

I’ve done several searches to no avail to obtain the information.

If anyone has this information or can point me in the right direction I would be greatly appreciative

One thing to remember is that when increasing diameter in wheels, you are decreasing the profile in the tires, giving the same total diameter as before. i.e. I went from the OEM setup of a 235 50 18 since I had the OEM 18" wheels. Now having the R Spec wheels my new tires are a little wider, but are 245 45 19. So my wheel size has only increased one inch, but my tire sidewall (profile) is smaller in order to compinsate for the larger wheel. This keeps the speedo and everything else the same, including keeping the tire rotations per minute the same.

 

[Skywagon]

Try below web site. Pop the $12. for the "Pro Comparer". I've been putting plus sized wheels and tires on cars for years and never have had a braking or computer problem. Yes, your speedometer may read slow but you simply have to be aware of it. The web site will tell you how much of an error to expect. Check the lower/bottom left hand column of the site for the "comparer".

www.rimsntires.com

 

[Gambler]

To sum up the comments, outside tire diameter is what really matters in the end. You can get various sized tires that are all of similar overall diameter. If you intend on increasing the overall diameter, then you can run into rubbing and speedometer problems.

 

[Skywagon]

Gambler, you are correct. Also, if you put wider tires on a car you are laying down more rubber and, consequently, adding friction which may reduce MPG. Conversely, stock wheels usually weigh considerably more than most aftermarket ones and lighter wheels can help MPG. Also, wider tires help handling too. I've always suffered from "Skinny Tire Syndrome". It's a malaise brought on by looking at a car from the side and being content. However, when looking at the car from the rear something seems to be terribly wrong. Mental illness is a terrible thing!!

 

[newman]

I think I read a thread somewhere in here about the effects of putting larger wheels on the car.

I think the thread said it was alright to go one inch larger that stock, but any wheels more than one inch over stock could cause problems with shifting and the indicated speed and the odometer.

I’ve done several searches to no avail to obtain the information.

If anyone has this information or can point me in the right direction I would be greatly appreciative

Here is another web site that I used (free). http://www.miata.net/garage/tirecalc.html

Cheers,
Newman

 

[Southern Boy]

Thanks to everyone for all the info and suggestions. Now that I had my head wrapped around this I can continue my search for asset of wheels for my Jenny.