Tires: Mismatched aspect ratio on tires, Winter Tire Size

Question
Barry -
I replaced my aging '01 Mazda Protege with a '04 Toyota Corolla.  Last winter, I purchased new snow times for the Mazda (tire size: P155/55 R15).  The Corolla's tire size is P155/65 R15.  With the difference in aspect ratio, the diameter of the snow tires will be slightly smaller than the summer tires.  So, I know that the MPH reading will be artificially higher.
While the snows should "fit" on the Corolla, am I introducing any other safety concerns?  The snow tires are in good shape and I'd like to get my money's worth out of them if possible.
Thanks,
 Ed in NH

Answer
Ed,

There is something wrong in the tire sizes you gave me.

According to Tire Guides a 2001 Mazda Protege originally came with P195/55R15's and a 2004 Toyota Corolla originally came with P185/65R15 or P195/65R15's, so we need to clear this up.

On every vehicle sold in the US, there is a sticker – commonly called the tire placard - that lists the original tire size and the proper pressure for that size.  The placard is usually located on a doorpost or in the glove box – but sometimes it is located in the trunk or on the fuel filler door.

Find the placard and verify the tire size listed there.

In both cases, the winter tires are not only smaller in diameter, they are also smaller in load carrying capacity - and that is not good, as this increases the risk of a load related tire failure, which sometimes has tragic results.

I'd recommend to sell you winter tires on eBay or CraigsList and buy the proper size.