You would be amaized it does have an effect on the tread pattern of a tire... For instance if you run a TSL Super Swamper Bogger on the road compared to a Kelly Charger the Kelly tire would have a better rate of gas mileage. For road use the quieter the tire then better the mileage. That was a good moto we used at Belle Tire. It can also be several other things as noted above. It is a Jeep they do weird things, thats what makes em so darn fun.