Wheel Offset & Tires On 09 Gmc 4x4

jason.hodge · March 3, 2010

Both of your guys trucks look good.

FYI-

08 Blk GMC sierra crew cab 2wd

2.5" CCM front level kit

Blk RBP 94's +10mm offset with machined face... wheels about flush with the widest top portion of fender

Cooper zeon ltz 275/60/20

A wheel store guy tells me 305/55/20 A/T would fit without rubbing... Hummm well maybe with the factory +35mm offset? Who knows.... I think the 285/55/20 would be a perfect size, but it's only in nitto 10 ply for a grip of cash, if you want all terrain tire. Well with my +10mm offset wheel, I'm about 3/8" (measured) from rubbing on inner plastic while turning, with the 275/60/20. I would say 275/55/20, or 285/50/20 would be a safer bet. Both a tad bit wider, but 1" shorter. I read and investigated for about 3 weeks, and determined everyone had their own opinion on what does/does not work. It appears if you don't want a lifted truck (other than 2.5" leveling kit), and dont want to cut or modify, stay close to factory offset, and stay in the range of 32" high, and no more than 12" wide... On the conservative side, I would probibly go with 275/55/20 for my next tire due to my rim offset. If anyone has the Cooper in 275/55/20, and wants to trade the 55 for the 60, I only have about 50 miles on the tires (2 days old). I hope my research can be helpful to someone...

I'm looking at doing something similar but I have been stuck on the new wheels. I currently have stock 18" - I think the factory backspacing is 5.5 and no clue on the offset. My question is if your going with wider wheel how do you determine what the offset should be. I have heard that you want to stay + or - 5mm of the factory offset but does that still apply if your going from an 8" to 9" or 10" wide wheel?

SeirraRR · March 4, 2010

Here is a couple pics of my truck with 285/65/18 on aftermarket rims. Not sure on the specs cuz I traded my factory rims for them with another member on here. I know that the are 18x9 is all. Hope the pics help.

dgreene396 · March 9, 2010

Well, I got the opinion of a couple of guys in a local tire shop before I took the plunge. They really didn't know exactly if I would have any rubbage. My thoughts were that if I have to cut or trim a little bit, well, so-be-it. I guess I got lucky in that I didn't have to cut or trim anything.

My wheels are 18"x9" with a +18mm offset. The Moto Metal 951's come with either a +30mm, a +18mm or a -12mm. I am a mechanical engineer, so I am all about measuring and calculating and figuring out everything I can before doing something.

The -12mm offset will stick the wheels outboard of the fenderwells. They would stick out 30mm (18+12) (which is 1.18") FARTHER than mine do. I went with the 305 width tires, and from the pic shown, I would not want them sticking out that far. Sling crap (rocks) down the side of your truck. Currently, my tires are about flush with the fenderwells in the front.

On the flip side, the +30mm offset will tuck the wheels up under the truck more than I was comfortable with, about 3/4" farther than mine. I was afraid of possible rubbage with the wide tires, and would not like the look as well.

Simply put, that is how I arrived with my setup.

jimbrown_1 · June 24, 2010

Does anyone know what the offset on the stock 2005 GMC Sierra 6 spoke wheels are? I'm looking to get some Ballistic Off Road 17X9 wrapped in 285/70/17 Michelins and they come in +0, +12, or +25 offsets. I think the +25 would sit under the truck too much and rub but the +0 or +12 offsets might work better. I have a front end levelling kit installed already, but do not want the tires to stick out too much from under the stock fender wells.