Santa29

Hi,

Thinking about getting 2010 19" rims to replace the 17s I have on my 2009. Wondering if this will cause any problems? Pretty sure the fit is perfect and should be no problems, but anything else I should be aware of? Do I need to change the computer on the Rx350 to register that I have 19s instead of 17s, I think this would affect mileage and maybe TPMS?

stunt66

The only problems you can run into on plus sizing rims(as long as theyre close to factory spec) are scratching them on curbs and damaging them on potholes but the 19" should still give you a pretty meaty tire so unless you hit a massive pothole at a high speed i dont think that is a real concern. I've seen second gens with the 3rd gen rims and fit wise they look to be no problem. Mileage shouldnt get messed up a lot unless the 19"s with the tires are way bigger overall diameter than your stocks. Go to 1010tire.com and use their tire calculator to compare sizes. Other than that I say go for it but good luck finding a set for a decent price.

Santa29

Since mine came with 17s I guess the computer is programmed to 17s right? but since these also come in 18s, can i reprogram them for 18 inch rims then my mileage shouldn't get messed up at all.

cjs18

The effects of a tire / wheel change to your speedometer, odometer and other road speed-related electronics can be estimated by looking at the number of revolutions per mile for the tires you plan to use as compared to the originals. Tire Rack and others show this number as part of the tire specifications. A larger number would indicate a smaller tire diameter.

Carver

It's all about rolling diameter. I went from 16s on my RX300 to 18s but by using tire size I kept everything relative as far as the speedometer accuracy.

I don't know the tire size on your 17s but run that through this calculator and you can determine the sidewall height you'll need on the new tire.

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

mandyfig

The classic miata page that we all rely on...