Hello again everybody. I am in the process of purchasing another truck, a 2001 Freigthliner Century which currently has aluminum on the front and steel on the rear wheels. I know that i can either get a discount on the price or get the dealer to put aluminum on the rear 8 wheels. How much do you think i will save on fuel and would it just be better to get a discount on the price?

I doubt that the fuel savings would ever be noticeable. What is noticeable is your available weight capacity (about 400 lbs) and the overall looks of the truck. Alums just look better.

__________________

the biggest gains you would see would involve goin to highway singles..up to 400 per axle im told...plus up to 10% better mileage due to less rolling resistance/sidewall flexing

Thats correct. Super singles are the way to go if you can. This way you don't have to worry about the inner steel wheel and you can save 800lbs on your tractor. every little bit helps.

they will try to just put 4 aluminum on the outside and kep the steels on the inside. I would stay away from that setup, it wears the tires out funny.

I'd go to singles too but they are pricey. I just love the way they look though!!

Lets take a different angle on this, and not specifically consider the weight savings. I happen to be a big believer in aluminum wheels, and I will explain why.

The brakes on your truck work by converting kinetic energy (rolling motion) into thermal energy through the friction of the brakes against the wheel drums. We use cast material as brake drums because it has a relatively high ability to absorb this thermal energy, while at the same time providing us with a reasonable amount of durability. However, as with all pieces of metal, they have their limits. Assuming that a brake drum starts out at whatever the ambient temperature is, it has the ability to absorb friction and absorb heat up until the point where it has absorbed all that it can. At this point, if we still need to stop, the brakes become ineffective, the dreaded "brake fade" which is really the brakes inability to absorb any more heat from the applied friction of braking.

To bring the brakes back to usable stopping power, we need to release that heat, or somehow transfer it to the atmosphere. Some of this is done through transference of the heat to the atmosphere through the outside air stream, and some of it is done by releasing that heat into adjacent metal parts, which can shed the heat into the atmosphere.

High grade Steel, used in steel wheels is an excellent collector of heat, but has the qualities of retaining that same heat, shedding it slowly. Aluminum will shed that heat much faster, transferring it to the air at a greater rate, but retaining that heat for a much shorter period of time.

In winter, if you were cold, if you heated an equal quantity of aluminum and steel to the same temps, the aluminum would reach it's hot temp first, and would return to the outside temp first. The steel would heat a little bit slower, but would retain it's heat and give it off over a much longer period of time.

So, applying this knowledge to wheels, we have the brakes trying to shed heat into nearby attached parts. Tha aluminum wheels will absorb that heat quicker than steel, allowing the brakes to more quickly reach the point where they have the ability to absorb more heat and provide more braking. The steel wheels will absorb the heat slower, and will take longer to shed that heat into the airstream. This means that brake fade is more likely to occur with steel wheels because they are a much less efficient method of shedding that heat and transferring it to the atmosphere.

By getting rid of that heat quickly, we have the best ability to make use of our brakes, and the brakes will have a longer life since they will spend less time heated to their maximum temperatures.

Now, since the two metals function entirely differently, I can think of fewer bad situations than to have a steel wheel inside of an aluminum one. Because the heat is being freely shed by one wheel, and retained by the other, you can have a disparity in the air pressures inside the tires. Air expands with heat, and the tire on the steel rim will have higher pressures and higher temperatures than it's partner on the aluminum rim.

Add up the appearance factor, the weight savings, the improved braking, and the longer brake life, and I see no reason to ever have steel rims on any tractor that I would own or drive. But I see appearance and weight savings as extra's, not a specific reason to have aluminum wheels. I have what I consider relatively solid reasons based on braking an safety for having them, The shiny part is just a bonus to me.

yes but if you have a flat going down the road you are stuck with buying another high priced tire and possibly a wheel late load so are the savings really worth it