I was about to purchase a set of GM 20"x8.5" wheels when I noticed this disclaimer at the bottom of the brochure.
"Larger-size wheel/tire systems may impact your vehicle's performance. For example, depending on road surface and driving conditions:
*You may experience a change in handling, stability and braking performance, tire and road noise, and ride comfort:
*You may note an increase in tread wear and/or steering effort, and a decrease in fuel economy:
*In snow or icy conditions or during off-road use, you will experience reduced traction." (note the word "WILL")

Granted, larger diameter tires will change the height above ground level of the center of gravity, ergo a change in handling; tread design can affect road noise; and, as another thread discussed, larger/heavier tires may affect fuel economy.

The questions are:
1. Why/how does larger tires/wheels cause increased tread wear? (Shouldn't this be a factor of tread wear rating rather than of tire circumference?)
2. How is it, the definite statement that larger wheels and tires WILL cause reduced traction in snow or icy conditions?

The questions are:
1. Why/how does larger tires/wheels cause increased tread wear? (Shouldn't this be a factor of tread wear rating rather than of tire circumference?)
2. How is it, the definite statement that larger wheels and tires WILL cause reduced traction in snow or icy conditions?

1. Larger wheel and tire combos will most likely change the suspension geometry and as likely as not, people that change tires and wheels don't get the front end re-aligned, or for that matter, experiment with tire pressure to insure proper tire-to-pavement contact. Also, a wider tire and wheel will "stick out" more putting more strain on suspension components...especially wheel bearings....and this can cause mis-alignment resulting in tire wear.

2. Well, I think you're probably reading to much in to the statement, but depending on tread design, a wider wheel and tire may actually be worse in snow and ice because of the wider foot print. Tall skinny tires work best in snow because they dig down into the snow and get a bite. It's kinda like the difference in walking in snow with boots or using snowshoes. Snowshoes keep you up on top of the snow...which is good if you're a human...very bad if you're a truck. AS far as ice is concerned nuthin'...in my opinion....works on ice except studs & chains, but you could argue that wide tires will act the same way on ice as they do in snow.

Remember, there are millions of people out there that do wierd sh1t with their rigs and GM has to protect themselves from the crazies especially the guys that say; "Hey baby, hold my beer and watch this!"....:D
JP