What are the size's that GM is going to offer with ford going with optional 20's I would think that GM would give us something bigger than a 16" rim?

With 245's being the standard size for the 2500HD's and the 265's optional for the 3500 SWR's, and 3.73:1 as the only option? Don't expect anything other the 16's available.

I would think that GM would offer at least a 18" rim. It would help with gorund clearance also.

how would an 18" rim help ground clearance?

There is ZERO benefit to running a larger than a 16" rim on a tow vehicle. That being said, you can get GM 20" rims from your dealer installed on your new truck before delivery. It has been true for a couple of years. Just like the bed cover and nerf bars, it's a "dealer option" authorized by GM and carries full warranty.

Well the larger the rim diamater equals into more ground clearance with the same size tire as on a 16" rim, right? Say a 285 tire on a 18" rim the truck would have 2" more clearance than the truck with 16's and a 285 tire. Correct me if im wrong on this.

Ground clearance is determined by tire dia.

My 285-18's are about a 1/2 shorter than my 285-16 AT tires. It depends on Aspect Ratio.

Your ground clearance is determined by the height of the tire, not the rim. The limiting factor as to how tall of a tire you can put on these trucks is the height(or lack there of when it come to GM) of the suspension.

The 20" GM rims I believe are 6 bolt pattern for 1/2 tons, not 3/4 ton.

Ok I see,I was thinking the taller rim(18) on a same size tire as the 16" rim would = more clearance. I was just wanting somethin to compete with ford as they have optional 20's with their chrome package.

Usually tires for larger wheels have a lower profile (aspect ratio) than tires for a standard wheel.

For example a 265/75-16 the height is 75% of the 265 in mm for a height of 199 mm.

I run H2's so I have 265/70-17's so the tire height is 70% of 265mm for a height off the rim of 185mm that is a 14mm difference on each side of the tire so I loose 28mm total height from the tire, but only gain 1" with the wheel.

I hope that is a clear as it is in my head (clear as pig slop):lol:

I guess it's just an optical illusion but the looks of the larger rim make's it look like it has more ground clearance.:think:

Heck I'd settle for a rim that was an inch wider! And, for us Dooley guys, another 1 1/2" of dual-tire clearance that will work on '01 models!!!
JP

There is ZERO benefit to running a larger than a 16" rim on a tow vehicle. I do....you can fit bigger brakes.
Check this out:
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H2 stock

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396mm (15.6") requiring 20" wheels

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460mm (18.1") requiring 24" wheels

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Exactly!!! Nice looking set...