GuiltyWhen one throws monster mud tires on trucks they usually change their axle ratios to keep the same amount of power... and rpm at a specific speed. And they usually overdo it for more power down low at the expense of revs up high.
How can that be possible? A friction roller will have to travel a greater distance on a larger wheel to make a single revolution of the wheel than it would on a smaller wheel. This means that a larger wheel will turn more slowly with a friction drive but go farther on each revolution, conversely a smaller wheel will make more revolutions with same friction drive but travel less distance per revolutions.That being said, if you have a friction drive, the tire size makes ZERO difference whatsoever on the speed. With friction drives, the speed is dependent on the friction roller RPM and diameter, and on nothing else.