Decided On Rims. Now How Big Can I Go?

jamesf0622 · August 25, 2010

I've decided on these rims:

http://bmfwheels.com/gallery/wp-content/ga...GMC-blk-05b.jpg

Specs are 20x9 with a 0mm offset. I have a '09 Sierra 2wd 1500 Crew Cab with a 2" RC level.

How big of a tire can I fit in there without any rubbing? I'd like to go with a 305/50/20. I'm planning on running the Cooper Zeon LTZs.

[email protected] · August 25, 2010

A 305/50 might fit, maybe with a little rub over bumps when truning and when backing up.

Matt_ · August 25, 2010

if you have mud flaps, you will need to remove them. you will probably have to trim a little bit of plastic at the outter edge of the back of the fender well also.... might still get some slight rub in that area where the pinch weld folds over too, but it'll be close.

You should consider doing a 1.5" or 3" BL as a backup plan.

FWIW, thats the exact tire/wheel combo illl be running in about 2 weeks. Im hoping that my 3" bl will allow me to put my front mud flaps on since my rockers get beat up, even with the steps on.

mxdirtrider56 · August 25, 2010

Yea like already said, you will probably need to do a little trimming or use zip ties to avoid rubbing.

jamesf0622 · August 25, 2010

I'll be looking forward to the pics! It's going to be a while before I get my setup complete. I'm in Afghanistan right now and still have a few months left. Much of my spare time recently has gone to looking at lots of pictures and lots of reading on this subject. I have learned that I can probably fit the 305s depending on the offset of the wheel, but I haven't been able to find anything specific on 20x9 with 0mm offset.

if you have mud flaps, you will need to remove them. you will probably have to trim a little bit of plastic at the outter edge of the back of the fender well also.... might still get some slight rub in that area where the pinch weld folds over too, but it'll be close.

You should consider doing a 1.5" or 3" BL as a backup plan.

FWIW, thats the exact tire/wheel combo illl be running in about 2 weeks. Im hoping that my 3" bl will allow me to put my front mud flaps on since my rockers get beat up, even with the steps on.

Matt_ · August 25, 2010

look a few threads down in the rims&rubber forum for the thread started by STINSAN3. he's running the 305/50/20 ltz's on 20x9 with +18mm offset.

you can see in his pics where the tire comes close to the fenderwell.... the wheels you want will push that tire .7" further out which will cause it to hit there. so you'd more than likely need to do some form of trimming or adjustment to get it to work.

jamesf0622 · August 26, 2010

I have read that thread. I know that the less ffset a rim has the further out the tire will stick. How do offset and backspacing relate? Is there a formula where you can figure out the backspacing of the rim by width and offset?

look a few threads down in the rims&rubber forum for the thread started by STINSAN3. he's running the 305/50/20 ltz's on 20x9 with +18mm offset.

you can see in his pics where the tire comes close to the fenderwell.... the wheels you want will push that tire .7" further out which will cause it to hit there. so you'd more than likely need to do some form of trimming or adjustment to get it to work.