Tires

I will assume you are asking for a comparison of typical sizes of line haul tires. These are 11R22.5, 11R24.5 and also 285/75R22.5 and 295/75R24.5

All things being equal, an 11R22.5 tire and a 295/75R24.5 tire are nearly the same diameter and would have nearly identical ground clearance. The 285/75R22.5 has the smallest diameter of the group and the 11R24.5 has the largest diameter.

The trend in line haul has been towards 22.5 tires and the 285/75R22.5 size in particular. Why? The 22.5 tires weigh less than the 24.5 tires (they are smaller and lighter). The weight factor is a positive in terms of the fuel economy. The smaller diameter can also contribute to better vehicle handling (lower center of gravity).

The downside to low profile tires is a somewhat greater chance of sidewall damage. This is why many pick-up and delivery fleets prefer the 11R22.5 size to reduce tire removals due to curb damage.

Not many fleets use the 295/75R24.5 sized tires. The 11R24.5 tires are popular for owner operators because they look macho.

Actually, in the US, tires standards are set by the Tire and Rim Association. This organization is composed of representatives of all the major tire and wheel manufacturers. Load carrying capacities are standardized by size and load range.

Smaller diameter tires will have the same effect as putting the vehicle in a lower gear. The torque will be increased. There would be very little difference in treadlife of the tires you mention (all other things being equal) but, since the engine RPM's are greater at the same vehicle speed for the smaller tire, fuel economy would be negatively affected.

In a product service bulletin issued by Goodyear, the following statements are made regarding nitrogen inflation:

Nitrogen gas, as an inflation alternative to air, is becoming more prevalent in the market place and is being marketed as a benefit to the standard practice of using air to inflate tires.

Over a period of time both oxygen and nitrogen are able to penetrate through tire casings. However, oxygen molecules and nitrogen molecules are different sizes with oxygen being a smaller molecule than nitrogen. The size difference in the molecules allows the smaller oxygen molecule to permeate through the rubber at a more rapid rate.

Goodyear supports the use of nitrogen, as an inflation gas, in all Goodyear, Dunlop, Kelly, Associate Brand and Private Brand products, based on the ability for a tire to retain pressure for a longer period of time. The use of nitrogen will not affect the tire warranty.

Please be advised that even with the use of nitrogen as an inflation gas, regular inflation pressure checks are highly recommended.