Wheel size vs. Torque

[jmac]

My winter setup overall diameter is slightly smaller than the stock setup. Ever since, I can break'em loose a lot easier than before. Even just on a hard exceleration they are having a tough time finding grip on dry pavement.

This got me thinking about how tire diameter and torque are related, if at all. If you had a super small tire wouldn't you just burnout all the time? If you had a tractor tire would the increased mass reduce torque? Or is torque, torque no matter how much mass is on your axel?

If you put your car on a like a mustang dyno would it show the same numbers no matter how big the tires were?

Now I know I'm giving up dry pavement grip with snow tires, plus the cold temps (<20) don't help, but its just been bugging me if size of the tire plays a factor as well.

[NickG]

One of the first things people ask on the RV forums when others inquire about a lack of towing performance is if they increased their tire size. Taller tires is like swapping your rear gear ratio. If you have a 4.10 with 31's and you go to 33's, it's like changing to a 3.90. Not exact, but you get the pic.

Putting smaller diameter tires on your car basically changed the ratio as it get puts to the pavement. There is a chart somewhere that shows it for the trucks. I'll see if I can find it.

[NickG]

http://izook.com/gearcalc.htm

I put in a 19 diameter with a 2.92 gear, then changed the diameter to 18. According to that chart, you would have to put in a 2.76 gear with the 18's in to equal the 2.92 with the 19's. You got more torque by going smaller but keeping the gear.

[igneon]

Originally Posted by jmac

My winter setup overall diameter is slightly smaller than the stock setup. Ever since, I can break'em loose a lot easier than before. Even just on a hard exceleration they are having a tough time finding grip on dry pavement.

The grip problems you are experiencing are most likely related to the fact that a winter tire isn't going to have the dry traction a summer tire has (given the proper ambient temp). Conversely a winter tire will have more traction on the ice and snow.

[El Tejano]

Wouldn't tire width be a bigger factor more so than tire diameter?

[baaboo2]

It depends what the real difference is too. 1" won't mean much, but 4" in diameter will. It's probably a combo of all above.