backspacing and offet

[KT2T]

I just put Fuel Revolver 20" x 10" wheels on my H2 and of the two available backspacing specs, 4.5" (-24mm ET) and 5" (-12mm ET), I chose the 5" backspace (-12mm ET). I used this site to help make my decision:

http://www.rimsntires.com/

They have a truly excellent site for giving you a visual representation, as well as notes for wheel well and suspension clearance, when comparing your stock setup to a proposed setup for a new tire/wheel combination. To get the full breakdown, they only allow limited access to that data before kicking you out since they want to be paid for heavy users. Since you may not be able to justify the cost for a one-time deal, even though you might need to try many permutations to find the right recipe, there is a work-around. If you are using Google Chrome, open a new incognito window and use this URL:

http://www.rimsntires.com/specspro.jsp?item=Wheel-Tire%20size%20comparer&sw1=315&ar1=70&bd1=17&rw1=8.5&et1=18&sw2=335&ar2=65&bd2=20&rw2=10.0&et2=-12

That's long and ugly, but I'll break it down for you. The latter half of the URL specs the existing wheel/tire combination and then the new combination as follows:

sw1=315&ar1=70&bd1=17&rw1=8.5&et1=18&sw2=335&ar2=65&bd2=20&rw2=10.0&et2=-12

sw1=315
ar1=70
bd1=17
rw1=8.5
et1=18

sw2=335
ar2=65
bd2=20
rw2=10.0
et2=-12

So, you can see how to structure the URL to get exactly what you need for different tire and wheel combinations. The first set of specs is the stock setup of the H2 and the second set represents my Fuel Revolver 20" x 10" (-12mm ET / 5" backspace) with an approximate spec for the Interco 37" x 13.50" x 20" tires that I wanted. Keep in mind that they don't have support for high-flotation tire specs so you'll have to make a rough estimate like I did (using 335/65R20 to represent 37x13.50x20). If you need help with this approximation then let me know and I can post a reply with a huge file of script-generated mathematical conversions.

Have fun.