4wd question

[Rameses]

I am not a telemtry engineer, nor am I a technology designer, but what I can tell you is that even though the wheel is only spinning that much faster on the outer diameter(based on your calculations), those sensors are reading from the inner hub close to the center of the spinning axis which is now turning at a greater velocity measured in a much smaller increment...one at with the formula of calulation for the computer is now showing a variance like there is a problem it has to somehow compensate for....generally speaking, that outer diameter it is measuring from is maybe in the 2 to 3.5 inch range....

The rotational difference is going to be the same, in percentage, whether you measure at the tires, hubs, axles where they enter the differential, or the two halves of the differential itself.

[Speedbag]

But, will the plane take off? 

....I hit some debris in the road and IZ'ed the sidewall of one tire.

[Rameses]

But, will the plane take off? 

I was actually contemplating slipping something about that into one of my posts.

[zooom]

okay...so...FWIW...I looked in MY owners manual on my 2005 Subaru Baja Turbo and the only thing it says is...

"All four Tires must be the same in terms of manufacturer,brand(tread pattern), construction, degree of wear, speed symbol, load index, and size. Mixing tires of different types, sizes, or degrees of wear can result in damage to the vehicles powertrain....."

now, it does not go on to say anything about parameters or define what is an acceptable difference in "degree of wear"...so take that for what it is worth, but it seems more like a legal sort of warning to cover their ass and give them an out if they chose to use it at some point in terms of getting out of a warranty claim, moreso than anything.

as a side note, refferring back to vehicles with more electronically based active traction oriented controls, as apposed to the passive style moreso used on most cars, I recall there being a tech bulletin when we 1st started seeing angle gear/transfer case failures in 99-02 Volvo XC's due to a tire being of a different size or "degree of wear" and corporate at that point, put out a definition of acceptable wear difference of degree, and I think it was something akin to no more than 3/32's of a difference between tires in wear differentiation.....


and yes...the damn plane will take off!...even after a 620 blew by it at 140mph!

[mitt]

It isn't just the magnitude of difference in wheel speed - it is the variation in wheel speed between all 4 corners - there is a "correct" speed for each wheel based on the speeds of the other 3...  If 1 wheel is different than the other 3 by a certain %, it might cause problem, but it would be inpossible to know what the variation limit is.


mitt

[Rameses]

It isn't just the magnitude of difference in wheel speed - it is the variation in wheel speed between all 4 corners - there is a "correct" speed for each wheel based on the speeds of the other 3...  If 1 wheel is different than the other 3 by a certain %, it might cause problem, but it would be inpossible to know what the variation limit is.


mitt

My guess is that less than 1 percent (in worst case scenario) isn't going to be enough to do it.  But that's just a guess.

There's one surefire way to find out though...

redxblack, tell us what happens!!   

and yes...the damn plane will take off!...even after a 620 blew by it at 140mph!

[redxblack]

There's one surefire way to find out though...

redxblack, tell us what happens!!   

YOU GOT A DEAL!

I checked my manual and it said the same "degree of wear" line, which is why I was worried about a warranty covering the set. Regardless, the beast is going on CL for CHEAP because I want it gone. It's got 185k and leaks/burns oil. It's a teenager's car/transportation special having outlived its good years. I doubt a newer tire will make/break the sale.

Cheers for the responses!  You lost me with the math. If you were talking history/literature/philosophy, I could hang. Math and cars and I'm floundering.