Tire diameter difference and AWD problems

[TBSSTony]

How exact do tire diameters have to be to not damage or burn up an AWD system? I know the Syclone/Typhoone guys run combos with similar overal diameters (285/40 + 335/35 or similar), but I know their AWD systems are different than ours right?

Just dreaming right now, but trying to learn too. From what I've read in the wheels forum, a 275/45/20 would be a nice safe tire to not cause problems up front with steering. But even that looks a bit narrow on a 20. So I was thinking if you could squeeze a steamroller in back like the Sy/Ty guys. But 305/40/20 is slightly undersized and 315/40/20 is slightly oversized. Guess I'm asking is how sensitive is our AWD system? Here's a chart:

Tire size / Sidewall height / Section width / Diam. / Circ. / Rev per mi
275/45/20 / 4.87 / 10.83 / 29.74 / 93.44 / 699.39
305/40/20 / 4.80 / 12.01 / 29.61 / 93.01 / 702.47
315/40/20 / 4.96 / 12.40 / 29.92 / 94.00 / 695.19

So will those 3-4 revs per mile create a damaging amount of wear? It seems so small, but I have no idea. Any more wear than someone who doesn't rotate their tires enough and has minute differences in treadwear? Discuss...

[EnvoyXL]

I have 295's on my 20's and they are plenty wide. I wanted something that would be wide enough to protect my rims from curbs and the 295's are doing the job well.

[TBSSTony]

I have 295's on my 20's and they are plenty wide. I wanted something that would be wide enough to protect my rims from curbs and the 295's are doing the job well.

No rubbing up front when turning? How much room is left in back to go wider?

[EnvoyXL]

No rubbing at all. I have 295 40 20 tires and my rims are 20X8.5 with a +50mm offset. They fit the edges of the wheel wells perfect. I am not sure how much wider I could go in the back because they dont need to be any wider. If you ever go look at a 295 street tire at the tire store you will see how big it actually is and most likely wont want anything bigger.

The 295 40 20 is only off on the speedo by 1/2(.5) mph at 55 mph I think. So you would have to be going 110 for it to be a full 1 mph off.

[TrailblazerSS]

Actually the 295/40/20 is 3/4" shorter than the 255/50/20 used on the TB SS. Your speedo would be off by about 3% indicating speeds higher (and racking up additional miles on the odometer) than actual.

The offset is different than the offset on the TB SS rims. Tire fitment may not be the same. The suspension is real close to the tire. Just won't work.

Also remember the stock TB SS wheel is 20x8 not 20x8.5 and 295/40/20 tires are approved for rims from 10"-11.5" wide. 8 or 8.5 is really too small to fit properly.

[TBSSTony]

Actually the 295/40/20 is 3/4" shorter than the 255/50/20 used on the TB SS. Your speedo would be off by about 3% indicating speeds higher (and racking up additional miles on the odometer) than actual.

The offset is different than the offset on the TB SS rims. Tire fitment may not be the same. The suspension is real close to the tire. Just won't work.

Also remember the stock TB SS wheel is 20x8 not 20x8.5 and 295/40/20 tires are approved for rims from 10"-11.5" wide. 8 or 8.5 is really too small to fit properly.

Sorry, I wasn't comparing to the stock wheel/tire. I was talking the 275/45 - the tire I'd chose up front - with the 305 and 315/40. Probably an 8.5" wide front wheel, and 10" rear wheel. All of these are much close to the stock 255/50 than a 295/40.

*Wait, you're talking 295/40? You're not even talking to me are you lol?!

[TBSS]

I still haven't given up on my staggered combo:

265/50-20 in the front: 30.4" diameter
295/45-20 in the rear: 30.4" diameter

Fronts will likely be on a 9" rim, rears on a 10" rim.

Here are the specs on Toyo Proxes S/T tires in those sizes:

Tire Size-----------Rim Width-----Weight-Diameter-Width--Revs Per Mile

265/50R20 112V---7.5-8.5-9.5.------42----30.4-----10.5-----683
295/45R20 114V---9.5-10-11--------40----30.4-----11.7-----683

[EnvoyXL]

I am sorry guys, I didnt realize the SS was different. I figured the clearances would be the same. The 295 40 20 wheel/tire combo I was using was on an Envoy. I am truly sorry if I confused anybody.

[ghoster]

I am sorry guys, I didnt realize the SS was different. I figured the clearances would be the same. The 295 40 20 wheel/tire combo I was using was on an Envoy. I am truly sorry if I confused anybody.

I get confused everytime people talk about tire sizes. Its all greek to me.:D

[B52GUNNER]

You could go 275/45R20 all the way around. They are about a 1/2" wider and 1/2" shorter they woould not rub and you could rotate them. I had staggered tires and wheels on my Mercedes C43, it get expensive real quick.

[TBSS]

You could go 275/45R20 all the way around. They are about a 1/2" wider and 1/2" shorter they woould not rub and you could rotate them.
Not necessarily. Do you have a TBSS? If not, I suggest you go up to one and try to stick your finger between the front tire and the cast piece attached to the control arm. Not gonna happen. That piece not only impedes getting a taller tire in there, it also impedes a wider tire, as the cast piece goes down as well as across and up. There is very little room to work with, and even a shorter tire may have issues if it goes further back toward the inside of the vehicle.