alright.... lets get started.. basically this post has spawned from a pretty long discussion with my driveline design prof. so i figured it would be worth the post.

If you get a chance to have your rims and tires off, take a measuring tape, or a string, with your tires at the same psi, measure the distance around them.In alot of cases the tires will have different diameters at the same psi.

What does this have to do with the differential? well, if your wheels spin at different speeds eg. turning, lack of traction, different diameters of tires.... it will put stress on the gears inside the diff. The smaller gears will rotate constantly if the wheels are not the same size. This is due to the different speeds of the shaft going into the differential.

Problem solver: after measuring the tires, take the largest diameter tire and the smallest dia. tire at the same psi. Inflate the smallest tire a few psi. over the max recommended tire pressure (being extremely careful of course) ie. Max 40psi, inflate to 43psi. Leave the tire in some sun, nothing too hot, but warm enough that the air will expand. After an hour or so, let some pressure out and re-inflate to the same psi as the others.

The air expansion will stretch the tire a bit, so it might take a couple attempts at this to get it right. After the first time, re-install the tires and drive it around for a few days then re-measure the dia. When the diameter of the tires are the same, you should notice an increase in mileage and it will be alot easier on the differential.

i dont know if this thread is any help or if im just goin to get flamed for it..
hopefully it helps.

-mitch

 

i don't think a tire would be able to "stretch" out that easily. they aren't steel belted for no reason. if that was the case, high speed driving along would do it.

 

"COUPLE ATTEMPTS" and if its not the case, why is there a max pressure set for the tire?

dont do it is my answer for you.

 

it's so you won't blow a tire.

 

very educated... good job. nevermind the post. if it doesnt seem to make sence to you, then it probably never will. Im in my final year of mechanical engineering for automotive product design, I know my ****... so its not like this an educated guess to fix a problem.

 

you have a good theory but i'm just saying that's physically imposible to do (stretching out a tire so it has a bigger permanate diameter). like i've said, a tire is designed not to "grow" as much as possible with pressure or speed with the steel or whatever belting material. thats the main purpose of the belting in a tire. dont get me wrong - i totally agree with you on the differential and it's actions, but i'm pretty sure this isn't the solution...


Modified by sinister357 at 1:57 PM 10/20/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by meotch &raquo;</TD></TR><TR><TD CLASS="quote">... it will put stress on the gears inside the diff. The smaller gears will rotate constantly if the wheels are not the same size. This is due to the different speeds of the shaft going into the differential...</TD></TR></TABLE>How does rotating at different speeds cause increased stress? Isn't that exactly how a differential is intended to operate?

 

yes, but not constantly at all time. if both side spins at the same speed, there's less wear and tear on the differential gears.