CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

New Prius/ Old Snow Tires

I traded in our 2006 Prius for a 2012 Prius last spring. I’m getting ready to put on the snow tires that I kept from the 2006. Those tires are 185/65 R15 880 and the tires on the new Prius are P195 65 R15 895. The dealer said the snows will work fine but the slightly different tire will effect the speedometer and odometer.
What’s your take on this? Is there a conversion formula? This would be a tough story to convey if I were stopped for speeding.
Thanks

Paul Tankel
Rochester, NY

Rather than worrying about speedometer accuracy, you should be worrying about the load-carrying capacity of those old tires. The last number in the tire size refers to load carrying capacity, and the old “880” tires do not have as much load-carrying capacity as the newer “895” tires.

Additionally, the rubber compound on those 6 year old tires may have hardened sufficiently to give you signficantly less traction than new winter tires would.

Between the potential for tire failure at high speed as a result of lower load-carrying capacity, and the likely reduced traction from old, hardened tires, I think that this is a very poor way to save money.

The difference in the speedometer/odo reading will only be 2% faster. So it’s not a big deal. But just the same if you were pulled over, I wouldn’t mention to the cops as it’s possible for them to hit you with an “improper equipment” charge as well. It would be unlikely though. I agree with VDCdriver though. The load carrying capability and the age of these tires are more important issues.

If you haven’t stored the old tires properly, their safety is v-e-r-y questionable, although a knowledgeable tire technician may be able to inspect them and say they may be OK. Hybrid drivers are too valuable to wind up having an accident with bad tires.

Another consideration: Driveability.
If your '06 snow tires were “energy-saving” tires you have the equivalent of a 2006 cell phone. The standard energy-saving tires on our '06 Escape hybrid were the worst tires we could remember – hydroplaning, poor handling, poor wet braking, etc. When we bought newer tires we felt we had a brand-new car. New eco-tires may be better (a site like tirerack might have some tests).

Yes, there is a calculator. Tirerack.com (or a similar site) can give rpm’s per mile for both sets of tire sizes (you’ll need to key in a tire size, then select any tire and look at the specs for that tire to find this), which you can use to estimate actual mileage changes, as well as tire diameter, which affects ground clearance. Probably won’t be a major change.

Good luck and thanks for buying a Prius (always nice when “somebody else” helps save the planet), but I agree with VDC that money isn’t the big issue here, especially with a new car.

It is normal to use slightly narrower tires for snows. But, I would stay with the given size and buy new ones. You will loose a little handling and I don’t like cookie cutter tires to begin with. But, technically the dealer is right as 185 snows with more aggressive treads are nearer the all season 195 size then you would think and the difference will be less then 2%. It’s a new car, it deserves new tires…don’t be cheap with tires. They are our only contact with the road, till you roll over.

I like a suspension lift on the Prius with 265/70R15s ;=)

I’d sell the old ones on Craigslist, etc. and get a set of new Michelin x-ice tires. If you need a separate set of winter tires, I’d get the best I could find.

I’d use the “old” snows on the new Prius. Often winter tires are a bit bigger due to more and deeper tread and some mfg’rs recommend one tire size down on winter tires. I don’t see how load carrying capacity would be significantly different and this isn’t a heavy duty truck we are putting the winter tires onto. You will lose a couple of mpg’s but you would have noticed the same effect on the old Prius. If these tires have good tread left on them I’d use them if I were in your shoes.

As far as speedo error I’d bet you wouldn’t notice anything significant. If you have a gps you can check the mph reading on the gps and the speedo to see if there is an error and compensate accordingly.