Canadian Hummer Club Forums

@johnnyspikesH3, sounds pretty straight forward.additional input will be helpful. thanks!

[quote name='Sugarphreak' timestamp='1325542212' post='34031']

Couple of notes for you G34:



-315/75R16 have a theoretical diameter of 34.6", however some manufacturers have larger or smaller so check the website out first.



-It will rub on your sway bar at full lock, this is not a concern as you will not be going very fast at all if you are at full lock and it just harmlessly rubs off the sway bar paint a bit. It doesn't really affect your turning radius.



-You may or may not need to crank your torsion bars. I suspect you will not need to, but every truck is different. If you get a little rubbing, it is easy to fix using the torsion keys. Just get yourself a really long breaker bar or impact gun and a 1-1/16" socket. Keep track of how many turns you put on the torsion key bolt, and do exactly the same to the other side. Measure the change as you go, once you reach your ideal height, take it for a quick drive and get the suspension settled down again... then re-adjust as needed. Ideally you raise the truck evenly OR take it in for a wheel aliment after (you should take it in anyway after doing this), keep in mind most GM's will lean to one side or the other (people believe this is due to how they get strapped down when shipping) so if the distance from the fender to the wheel on one side is more than the other do not be concerned.



[media]http://www.youtube.com/watch?v=FRIsmboMwDs[/media]



-as JohnnyspikesH3 said, keep it to 2" or less of lift or it will begin to affect your vehicle ride



-You won't need new torsion keys, I know this from experience... I have a set of Daystar keys and found out after the stock keys would have been just fine.



-Other option such as Samco shackles for the rear are out there if you need them, for this size tire you will not though.



These tires will work no problem... so long as you don't use an aftermarket rim!!



Your cost to do this will be buying and mounting the tires, buying a 1-1/16" socket and doing a wheel alignment later on.



Have fun!

[/quote]

hmm, i'm sure now that i'll be buying those 315's, i won't be using other rims as i want to keep the cost down. i really appreciate it Sugarphreak.thanks!

Just a heads up G34, I had the 35"s on my automatic 5 cylinder H3 and the tires made my fuel economy go to crap! Highway performance suffered quite a bit as well and it didn't like getting out of 3rd gear, or would constantly hunt 3rd to 4th with cruise control on. I get better economy now in my H2 than I did in my H3 with those tires!



Now the V8 H3 is another matter and should have sufficient power to get around on the bigger tires.



Last thing to keep in mind... your speedometer will not read accurately with the bigger tires, as well as your odometer will not record miles traveled correctly. In order to calibrate the H3's computer (this applies to the 5 cyl only) you must send your PCM to an aftermarket company for reprogramming. The V8 again is better off as you can buy a handheld programmer to adjust for bigger tires.



SO! Just FYI as I've been there and had the big tires, they're great on the trails and look awesome on the H3 but it's not all roses!!!!

Yeah the speedometer will be out by about 6%... so if you are traveling 100km, you are actually going 106km... 50km = 53km... ect.



I personally have done no PCM tune on mine, although I am stick shift so I had an extra gear to play with to start. And hey, it will get me 6% more on my warranty, lol.



For an Auto with a 5cylinder you may want to talk to these guys eventually. www.pcmforless.com They can send you a tuned PCM chip which will correct your speedometer and your automatic shift points to better match the tires.



I'd take a wait and see attitude though