What size tires did 4x4's come with stock?

Whats the biggest tires you can fit on a 2 wheel drive without a lift on stock rims. When does mileage really start to suffer?

Stock is 245/75/R16

I have 265's now and when you turn the wheel all the way to one side they do rub a bit on the mud flap on the inside of the wheel well.

Jacob

I'm also running 265's. They scrub just a bit turning while compressing suspension some they don't scrub much at all on the level at least don't notice it after a lot of tread has worn off.

Depends on tire and gearing. Mine's 3.73 and my 265's all terrains may have helped mpg some. Larger than 265 and aggressive probably will hurt. If you have lower gear maybe not so much. Higher gear I don't know.

I ran 285's on my stock steel rims for a year and they never rubbed. Then i got my new rims and I had to trim the plastic under the bumper.

Stock is 245, but I noticed on both my Chevs and my dodge that speed verified by GPS reads slower than what the truck speedo says. all 3 trucks speedo was correctrd with 265 tires, speedo was off by 5-7kmph, with the 265's it was bang on.

My Blazer 4x4 came with 265/75, the last 4 sets of tires have been 285/75 no problems.

The Z71 package came stock with 265s. I just got a set of Toyo Open Country AT and like them so far.

This post will likely get moved over to the tire section. There are a bunch of really helpful guys over there that know lots about tires.

Dave

I went to Belle tire here in Michigan,, and they guys told me I can put 265's on ,, but If I got 285's,, because its a diesel,, I would have to reprogram my tranny,, or the shift points would be all screwed up.
{I've been doing body work for over 20 years,, and I ain't never heard anything stupider than that!}

With 4:10's I thought to go 285s would be taller and make my 4:10 more like a 3:73 or closer anyway,,, IE better MPG.

With 3" lift on body,, I ain't worried bout no stinkin scrub!

Mileage won't suffer with 265's one bit. In fact, in many cases, the speedo is a bit "fast" with the 245's that are stock.
IIRC, 2wd and 4wd Duramax's are the same height. You're going to have the same issues that any 4x4 owner will have. 265's either won't rub at all, or may just BARELY. If you want to run 285's, then you're going to have to crank your tbars at least. If you tow at all, I would steer you away from stock rims on 285's. It is too narrow a rim to put on the 285's and you'll get funky wear patterns and a good amount of sidewall flex.
If you want to keep your stock rims, go 265's. If you want a bit more and don't want to spend much, go with some H2 takeoffs for a couple hundy and throw on the 285's.....
My $.02

I bought my truck a month ago and the tires it came with are mismatched :(

The fronts are 245/7516 and the backs are 235/85/16

I just got some of the newer GM/Chevy 8 lugs off craigslist, the tires they came with are bald so Im gonna have to transfer my tires onto them.

Can I go 285/75/16 in the back and put my 235/85/16's up front?

My 235/85/16s are basically new and I found a great deal on 2 285/75/16's

If this is a dumb idea let me know

n/m didnt realize 285/85-16 was 35 inches