Hey guys I'm new to the whole Diesel world as well as a dually. I have herd some of the local farmers talking about running a smaller inside dually tire to save on some tire wear and a small amount of fuel mileage gain until you put a load on the rear end causing the outer duals to settle and allow the inner tires to make contact with the road and support your heavier loads. Has anyone tried or herd about anyone doing this? If so did it make a any difference in tire wear ect? I am currently running 235/85/16s was thinking about going to a 235/75/16 which is a little less than a inch smaller on the inside duals but don't want to waste the money if this is all just a old wise tale..

 

I used to work in the commercial tire business and I've never seen or heard of such a thing.

 

I ran a smaller tire on the inside by mistake and it wore the tire out quick as ****. The smaller tire spins faster and therefore rubs the ground wearing the tire out.

 

ok thank you for the quick replies. I'm gonna take it as old wise tale. thank you for the info. Gonna save some $$$

 

The wheels are bolted together and therefore one cannot spin faster... so many rpm.

 

That's what I thought too. But if you hold a 20 foot rope and spin in a circle. The 20 foot mark spins way faster then the 10 foot mark. And having done it myself I speak from experience

 

this is a horrible idea. to prove it, roll a base ball on the ground 10 full revolutions, then roll a basket ball 10 full revolutions. Different distances right? but if you bolt the baseball to the basket ball then one of the two (usually the baseball) will scuff on the ground causing quicker tire wear and lower fuel economy due to more rolling resistance. now replace the ***** with tires and there ya go. hope this helps.

 

Tire speed is a function of rpm and radius. The rpm is the same for both tires.

If both tires are in contact with the ground, then regardless of tire size, they have the same rolling radius.

Therefore: The LARGER tire will wear faster (from carrying most of the load), But less fast than if the smaller tire were removed completely.

For the baseball/basketball thought experiment to work, there must be two sets of them connected by a concentric axle.

 

I'm simply stating facts that i learned while doing alignments and tire service on semi trucks. there is a reason that they have the same size tire. how much weight is on the tire hos very little affect on wear rate. the reason the smaller tire will wear quicker is because is has a smaller circumference than the larger meaning that per one revolution it has to travel farther. since the larger tire will have most of the weight on it and there for, more traction, the smaller tire will be scuffing on the road eating miles off its life. I know that i am right due to real life experience. I'm sorry if you disagree.

 

There are many reasons why tires wear at different rates. It is Not because one tire travels further...It does not ...it can not.

Conclusions derived from real life experience are not facts.