"Paul M. Hillbish" wrote:

> Tires. I have a question about tires. On the front, I have a different size
> tire than on the rear. The wheels are the same size though. My question is,
> how will this effect performance? Being that I am poor, I will not be
> replacing the tires very soon, but I am wondering, should I have the larger
> ones on the drive wheels? Any thoughts on this?
>
> --Paul--

Paul:
 Assuming that your van is 2 wheel drive, this is not a big issue.
  If there is any difference in the load rating or max psi , put the pair with
the largest numbers on the rear.
  Putting the best tread on the front will give you better braking on wet
pavement.
  Having the tires with the largest overall diameter on the back will give you
a little better mileage on the hiway but a little less acceleration at low
speeds.  Calculating the gas mileage from odometer readings, however, will not
detect a difference because it only counts wheel revolutions not actual forward
progress.
  You didn't state the actual tire sizes.  All 3 numbers determine the overall
diameter.  Often increasing the first number and decreasing the second number
can give about the same diameter, depending on tread wear and pressure, etc.
  To compare, you could measure carefully how far the van moves forward for
exactly one turn of a tire while supporting the expected load with the proper
pressure.

Larry A.