Tire size?

[Craig 85]

Here's a couple of my prior trucks. '85 C20 no lift with 33x12.50x16.5's with 9.75" wide wheels (4.75" BS). No lift minor trimming on the front of the front fender. Same tires were then installed on the '80 3+3 when I sold the '85. Here I added Air Lift air bags in the front coils and a 2" block in back to keep the original rake. Minor trimming at the leading edge of the front fender.

I would guess you can run 286/75R16 with an 8" rim with no lift or rubbing.

You must be registered for see images attach

You must be registered for see images attach

 

[Differentdanyou]

Here's a couple of my prior trucks. '85 C20 no lift with 33x12.50x16.5's with 9.75" wide wheels (4.75" BS). No lift minor trimming on the front of the front fender. Same tires were then installed on the '80 3+3 when I sold the '85. Here I added Air Lift air bags in the front coils and a 2" block in back to keep the original rake. Minor trimming at the leading edge of the front fender.

I would guess you can run 286/75R16 with an 8" rim with no lift or rubbing.

You must be registered for see images attach

You must be registered for see images attach

How much trimming did you do on your c20?


Sent from my iPhone using Tapatalk

 

[Craig 85]

How much trimming did you do on your c20?


Sent from my iPhone using Tapatalk

On most of my trucks I cut it here at the red line in the front. Then reattach the screw at the yellow star. On my 4WD's I do the same at the rear of the fender.

You must be registered for see images attach

 

[Bextreme04]

My stock ‘74 C20 had no problem clearing factory 2011 2500 rims with 275/75R17’s on it. That’s roughly a 33x10.5” tire. I used 2” Adapter spacers to convert from the 8x170 to 8x6.5 and have the wheels fit the narrower axles.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

It never rubbed, even with several thousand pounds of stone in the bed making it squat pretty hard. The only reason I did it was because the old 16.5” rims/tires were terrible and I got the set of stock tires/rims for $50 with basically brand new tires on them. Adapters were only $100 brand new and included the correct lug nuts.

 

[shiftpro]

At stock height, I've found you can get away with bigger tires on a 2wd vs a 4x4. The front track is narrower and the suspension geometry keeps the tires off the fenders.

I've run various "33's" on my '78 C20 and nothing has contacted the fenders. I've run 285/75/16's on stock type narrow rims, 12.00x16.5's on 9.75" wide rims, 33x12.5's on 9.75" wide rims and it has all cleared the fenders fine. I'm currently running the 285's up front and 35x12.5's on the rear and I'm considering running 35's up front just to see how well it may or may not work. I'd have to trim the fenders though.

Also, as you know, a 4x4 with a lift spring will move the wheel back as the suspension compresses. I'm mentioning this for anyone else dropping in..

As for trimming your fenders, have you had your cab off recently? If your body mounts are in good shape, if the hardware is not rusted up, you could try slide the cab back on the frame. It might not go, or it might slide back 3/4 - 1". Suddenly you gain clearance! Of course the box needs to slide back too, so this might be a stupid suggestion after all.
The added bonus, as little as it may be... every pound you can take off the front wheels and put on the rear is a win. I don't know how much weight bias will change with such a small adjustment but I look at as every little bit helps. I'll spend three days with a die grinder for 2 hp. (on MY engine, sorry not yours!)

 

[El Perdido]

I have not found a reason or terrain in the 27 years of owning my K20 Suburban for a lift or tires larger than the stock 235/85r/16's. The truck had 70K on it when I bought it and while most of the 355K I have driven it has been on pavement, a significant portion has been on the 4x4 roads in the Colorado mountains, but also in the Mojave, Sonoran and Chihuahuan deserts.