Blackbear tune

calsdad wrote:

Chevy and GMC offered an optional 20" rim with a 265/70-18 tire in 2012. The 2012 Silverado/Sierra body was the same as the earlier years (front wheelwell was the same is what I'm getting at).

The OEM tire size that is on my 2010 Yukon 265/ 70R 17 which is 31.7" in diameter. The optional 20" tire is 32.7" - and the LT285/55R20 that I'm thinking of going with - is 32.4" diameter (took all the dimensions from Tire Rack)

I've searched high and low and compared part numbers for fenders on 2007-2012 Silverado / Sierra's - and from what I can tell there is no difference between the trucks until 2013 ( I think it was) - when they went to the newer body style. I've also looked at a number of Silverado / Sierra's - and compared their front wheelwells to the ones on my Yukon - and they look the same to me.

Lastly I took some spacers against the current tires and rotated the front tires thru their turning radius - and it sure looks like the 20" tires will fit in the wheelwells.

I find it hard to believe that GM would offer a 20" tire size that simply did not fit. My last resort is that NorCal performance has a pretty detailed How-To on their site on getting more clearance in the front wheelwells that doesn't look too hard to do.

So - long story short, I'm pretty sure the 20" tire size I'm looking at will fit with no or very little wheelwell mods. GM fitted a slightly larger tire.

I'm also contemplating going with a very slight lift in the front. It's "factory" now - and there's about a 1.5"-2" rake from front to rear. It could stand to be lifted in the front an inch or so to level it out. I've been meaning to talk to NorCal about what my options are and just need to find the time to call them.

I think it's the extra width that gets you, not the height. I forgot about the optional 20" rims that GM offered, I didn't realize that they had that big of a tire on them.
I would just crank the torsion bars to get rid of some of the rake. I think it looks better more than really any functional thing.

As far as brakes goes, if they let anything under 10K NOT have brakes, that is crazy! In Texas if it is over 5k it better have at least 1 axle with brakes! I wouldn't want it any other way.....