Replacing Durango 31x10.50-15 wheels/tires with 17"

[This name is al]

My 1998 Durango has the 31x10.5015 tires on it & I want to add 17" R/T wheels.

I've studied this a little bit & found that the Dakotas use one size of 17" tire (255/55) and the R/T Durangos use another (265/70).

I checked the online tire size calculator (http://www.miata.net/garage/tirecalc.html) and since there is no listing for the 31x tires I went to a tire dealer website & found the 31x tires range from 30.4-31.0" in diameter. I used a 265/75-15 tire as a standard since it is 30.6" in diameter.

Here is the issue:
The 255/55 tires are only 28.0" in diameter, which would increase my highway RPM and throw off my speedo by about 8.5% (5 MPH @ 60 MPH). The 275/60 tires are 30.0" in diameter, with an error of 1.3 MPH @ 60. If I want to keep my speedo correct, according to the calculaor, I would need to run 285/60 tires (30.5" diameter, .4 MPH error @ 60).

Based on the reviews I've read, the Kumho STX tires are the best for this application. Fortunately, they are available in the 285/60 size.

Is anyone running this tire size? Any fitment problems?

[Neil]

The Durango R/T came with 275/60/17 which is a tiny bit small than the 31's. http://www.durangoclub.com/faq/DurangoTireCalc.html Your speed will only be a little off. The Dak R/T came with a smaller wheel.

[This name is al]

Thanks for the link- I ordered 285/60-17 Kumhos.