wheels for winter tires

Since the Prius sits so low, and the transmission won't let your wheels spin in snow, winter tires are essential anywhere you get snow. Some people like to buy an extra set of wheels along with those tires. What are the pros and cons?

The basic tradeoff is having to mount and balance tires twice a year versus the one-time cost of those wheels. Mounting and balancing 4 tires costs about $50 twice a year, whereas a set of 4 cheap wheels costs about $200. And with two sets of wheels, you can switch summer and winter wheels yourself, and you avoid cosmetic damage from repeated tire mounting. A popular choice is to put winter tires on the stock 15" wheels that came with your car, and buy nicer 16" or 17" wheels for the summertime.

The tire pressure monitoring system (TPMS) adds a wrinkle to this decision. The TPMS units sit inside the tire, opposite the valve stem. The only way to move them from one set of wheels to another is during tire replacement. (Though they will fit your 17" summer rims.) So if you want two sets of wheels, you'll have to buy a second set of TPMS, or go without for part of the year. At $400 for a set, plus a $150 tool to pair the sensors to the car twice a year, most people choose to go without during the winter.

Running without TPMS in your wheels turns on a steady yellow light on your dash. No beeping. Some people just ignore it, some people put tape or a sticker on top. On the Gen III (2010+) it is possible to disable the TPMS light with a jumper. Find the TPMS ECU in the "ECU Integration Box" located behind the glovebox:


Disconnect the TMPS ECU and jumper pins 5 and 7 on the connector. You can do this with a small paperclip cut and bent into a U shape. Here's the connector, viewed from the back of the connector where the wires are:


The plug has 12 connections, but actually each connection has 2 holes. One is a rectangular slot within which you can see a metal clip; the other is a round, smaller hole. THAT is where the jumper wire goes. Round wire into round hole.
Another trick is to mount the TPMS sensors in a small PVC manifold that can be pressurized and stuck under the seat regardless of which tires/rims are mounted. Many people have thought of initializing the tire pressure setpoint to zero, but that doesn't work.