Hello and HAPPY Memorial Day weekend to my fellow HUMMER fanatics. I have a question. What's the largest size tire I could fit on my 09 HUMMER H2 without having to re-gear? I previously owned a 05 HUMMER H2 SUT, which was already lifted from the previous owner. The 05 model H2 had 38 x 13.50 R22 tires. I'm not sure if the previous owner had the HUMMER re-geared prior to getting those 38's installed. Any thoughts or exeperiences installing larger size tires on a H2?

 

I have 37" 13.5 20 on mine for 17 years, did not have to re-gear

 

After researching the internet and talking to a couple of friends that are mechanics and offroad racers, I went with 37" on 18" rims (Used 18" rims because there are not as many options in 17" - I was told that 17" rims are better for off road as they have a lower failure rate than 18"). Since my 2005 Hummer H2 is an everyday driver, I opted for XD811 Rockstar II - Matte Black/Accents Rim 18x9 (XD81189080700) and 37" Hybrid tires (Nitto RIDGE Grappler (HYBRID) - 37 x 12.50 R18.) I stuck with 12.50 width to avoid future problems that the stress would put on the system.

MY 2005 Hummer H2 is an everyday driver, so I didn't want any clearance issues (Some people have no problems with 37" and some people do not) and I wanted the ride to feel like stock and not to have extra strain. I realized that the best way to do this was to use a torsion lift, with upper control arms with better geometry and joints), The easiest way to do this was to go with the KRYPTONITE STAGE 3 LEVELING KIT WITH FOX 2.0 PERFORMANCE SHOCKS 2001-2010. Well work the money - looks and rides awesome.
The only thing I notice is my speedometer if off by 3mph.

 

The 05 came with 4:10 gears standard and the 09 comes with 3:73s (a mistake on GM's part in my opinion), I've got an 08 and have true 37"s on it. I live in the south were other than the occasional overpass/bridge its flat. With the double overdrive in our trucks mine was in and out of 6th all the time and struggled to maintain speed on windy days, I'll say that even with the stock tires it was almost as bad as with the larger tires, didn't see much of a difference when I swapped over to larger tires. I started with the engine (had lifter issues) pulled and upgraded it then drove it for a while like that, was a lot better but still not what I thought it should be so moved to gears.

I did as you did and added UCA's and a leveling kit with Bilstein shocks when I added the larger tires, the shocks improved the ride for sure (i stayed with the OEM 20" wheels)

My truck performs as it should in my opinion now, at 70 to 75 mph the truck stays in 6th for all but the steepest bridge.

Neal,

 

I appreciate your feedback. I've already installed a 6inch suspension lift by Full Throttle.

 

I appreciate the feedback. The wheels/tires seem like the hardest thing to put on this Hummer and the most expensive to really bring this vehicle to life. I wish I never got rid of my 05 SUT. The previous owner(s) already had a lift kit on her, with dual cat-back exhaust, 38x13.50R22 inch tires. This 05 HUMMER took steep hills, bridges and overpasses like a champ. So, I'm not sure if the previous owner re-geared her or not. This is my first project H2 I'm trying to trick out from scratch.

05 HUMMER SUT

 

Good looking truck

Neal

 

 

Most people NEVER re-gear, ever, no matter what tire sizes. To do a re-gear is not cheap, big tires and wheels are not cheap either. Once the bigger tires (and perhaps wheels) go on and the wallet is deflated, most blew the wad and they are done.

Check out the price of a re-gear at any local diff service shops and you will see what I mean.

Unless you are going to do some serious wheeling and/or rock crawling, you really do not need a re-gear. Now, if your diff(s) need service and are due for a rebuild, that is the time to explore your question.

 

I got the post by Jack America and yours mixed up, didn't look at who posted when I responded, reason for the UCA and shock comment.

You've got a good looking 09 H2 there,

Around here its around $2500 for a gear change, I spent around $1200 for the gears and a few specialty tools and did it myself.

Neal