[A4] tires, speaking of tires, anyone have any used 17's lay'n around?

[Rocky Mullin]

On Dec 27, 2007, at 10:57 AM, Sean Reifschneider wrote:

> On Thu, Dec 27, 2007 at 01:14:33PM -0500, Huw Powell wrote:
>> Yes, but forcing a differential to constantly rotate to make up for  
>> tire
>> diamter issues is hard on it.
>
> It's a matter of degree.  As I said, you will almost never have  
> exactly
> identical rolling radius on the different tires.  The difference  
> between a
> brand new tread and one that's at the wear bars is around 7mm on these
> types of cars.  That's just over a quarter of an inch.  Brand new  
> tires
> inflated to exactly the same pressure will be close.  But, the  
> fronts wear
> faster than the backs.  Oh, and don't ever park your car so that one  
> side
> of it is in the sun, that'll cause the pressure on that side to be  
> much
> larger than on the shaded size.
>
> How far do you really want to take it?

just far enough to do the math, really.  punch in the numbers, the delta
of that quarter-inch per rotation.  how much diff wear per mile?  per
20,000 miles?  like i said before, it's your car, do what you want, and
you totally will.  i shouldn't even care that much, since i lease and
won't even get through a set of tires in three years (25 months and just
hit 18,000 miles).  on a car i owned, i would care.

as far as the other examples, yes, variables have influence, and we all
have to concede that.  we can do that without throwing out the baby with
the bathwater, though.

it's better for people to understand all the issues to make informed  
choices,
rather than just saying it's no problem either way.