PDA

View Full Version : 22" Wheels vs Gear Change



Stratosurfer
06-15-2008, 20:15
I'm considering moving to larger wheels for a taller tire circumference. Anyone mounted 20 or 22" wheels on an 8 lug Suburban .75 Ton? I have tall tires now on the 16" wheels but this leaves a lot of 'freeboard' on these tires and I would have to believe the truck would handle better with less sidewall. As well I believe I could do the wheels and tires for about the cost of 4:10 to 3:73 gear change, possibly considerably less and end up with a similar overall drive ratio.
I don't know if the circumference required to equal a 3:73 would scrub anywhere, these are the things I'm hoping someone has already done or researched.
Thanks

DmaxMaverick
06-15-2008, 20:38
Wheel size means nothing to final drive ratio. Nothing. It's the tire size, or diameter, to be more specific. You can have larger tires on 16" wheels than with 22" wheels (unless you run class 8 tires). Just because of availability. A real disadvantage to larger wheels is ride harshness and lost capacity, within the same ply rating. Tire volume (the amount of "air" it will hold, not the pressure) determines capacity within a ply rating. More volume, more capacity. Less volume, and you get less capacity, and less shock absorption (ride harshness). Choose carefully. You may not like what you end up with. Less sidewall is a more firm stance, but it comes at a cost. I've run 33" tires on my 2001 HD (285/75/16D), and they do very well handling the 13K+ 5'er I tow. Many thousands of miles and no issues.

MPrichard
06-18-2008, 20:05
On my 93 Sub, I run stock Hummer H2 wheels and tires (315/70-R17) which is just a 17" rim, but it's a 35" diameter tire which certainly brings your RPMs down. If you start with a 235/85-R16 (stock size for some of these trucks) with 31.7" diameter, and bump up to 35", that's the equivalent of a 4.10 to 3.73 ratio change. There are many simple ratio calculators online:

http://www.izook.com/gearcalc.htm
http://www.csgnetwork.com/multirpmtirecalc.html

Here are a couple to help sort out the different tire sizes and ratio combinations. For what it's worth, H2 tire/wheel combos are frequently available on eBay nearly brand new for very good deals (I got mine for ~$175/tire-wheel for 6, all new). They required some fender and bumper trimming in front, and I put 2" wheel spacers in the back, but it rides like a dream and handles significantly better.