Tire size question.

[gumbys10]

Anyone know what the widest tire/rim combo you can install on the rear of a halfton lowered 2wd suburban. Factory wheel tubs and c notched only. Not looking to cut up factory interior for a couple years. Wheel size and offset would also be appreciated as I can convert the measurements to the size I need. I am thinking centerline smoothies, 20x8 on front and 20x10 on rear, but would like some meats under the back like a 315/35/20 if they'll fit. Pictures of clearance would also help.

[AzDon]

I don't do the "big wheel" thing, but I can tell you how to figure this out for yourself, so that you wont be disappointed with any bad advice.....
With your rear axle on jackstands, lay a straightedge (on edge) across the wheel mounting surface that extends up into the wheelwell and measure to the inner and outer points of the wheelwell to get you total inside/outside clearances. This is the info you will use to determine your width/ backspacing. Next, measure from you axle centerline to the top of the inner wheelwell and subtract any future lowering AND whatever clearance you'd be comfortable with. This measurement is HALF of the overall diameter of tire you can use.
Next, go to tirerack.com and shop for tires by size and click on specifications and you'll eventually (after a bit of surfing) get to a chart that shows overall height, tread width, and section width. Pick a tire with correct section width and diameter to fit the rim size you want and you are good to go!

[AzDon]

A couple of other things (since I dont see an edit button):
1) be sure the backspacing/fenderlip measurement is the same on both sides of the truck, or else your axle is being pushed off-center by the trackbar!
2) You should still perform the backspace/frontspace measurements, but I can tell you from experience that the bolt faces on the stock rear axle are just about exactly centered between the stock inner wells and the fender lip.

The whole process is basically about choosing the gross height and width of tire that will fit within the opening and fit your desired rim size first. Then selectig that size rim with the correct backspacing.

Another thing you should consider about the "tall rim" thing is that using a 15inch rim instead of a 20 means that the same "profile" of tire is going to result in a 2.5 inch lower vehicle by itself, meaning that you hafta use a 35 series tire on a 20 inch rim to be as low as youd be with a 70 series tire on a 15...
A 60 series on a 15 inch rim works to enhance your lowering job and the wheels and tires are cheaper, ride better, and last longer!

[gumbys10]

I am currently installing a watts link, which will keep the diff centered with all up and down movement. I like my tire fitments to be as close to the outside edge as possible because to me it gives it sort of a muscle look to it. As for the big wheels, it makes the suburban not look so large or "heavy". Helps with the proportioning. I am a hot rodder at heart, and I like the same size wheels front and back, but big and small tire combo's. The look I am going for is more stock, but slammed, so a body colored center of a centerline smoothy, with a factory dogdish hub cap to hide the lugs and give it a 20 inch steel wheel look. As for measuring, I would love to, but it is in storage 30kms away from me for another month, and I would like to start ordering parts as it takes forever to get them up here in Canada. I was just gonna take what ever sizes people had and subtract a bit for safety and live with the setup. But as you say measuring is the best option, but I am impatient.