On rim vs off rim tires

Two jobs with the same name

When you book a tire change with 2 and 1/2 Mechanics, the booking page asks you to pick one of two. An on rim change is $75. An off rim change is $140. Both are before tax. The gap between them comes down to how much work each one takes.

An on rim change is a swap. Your winter tires are already mounted on their own wheels, so we take four wheels off the car, put the other four on, set the pressures and tighten the nuts to the right torque. Your summer set goes back in your trunk.

An off rim change is for a car with one set of wheels. Each tire has to come off its rim and the other tire goes on. That means breaking the bead, working the old tire off on the tire machine, mounting the new one, sealing it, inflating it, and then balancing every wheel. Then the wheels go back on the car.

Why a second set of rims pays off

Do the arithmetic on the posted prices. An off rim change twice a year is $280. An on rim swap twice a year is $150. That is a $130 difference every year, and over a few seasons it covers a good part of the cost of a set of steel winter rims.

The money is only part of it. Every time a tire is pried off and back onto a rim, the bead takes a little wear, and so does the rim edge. Pressure sensors inside the wheel get handled each time too. With a second set, nothing gets mounted or unmounted until the tires are worn out.

There is a salt argument as well. Plenty of people keep their good alloy wheels for summer and run plain steel rims in winter. Steel rims are cheap to replace, they shrug off curb rash from snowbanks, and the alloys stay out of the slush from November to April.

And there is a timing argument. In late October and November, everyone in the city wants their winter tires on in the same two weeks. An on rim swap is the quicker job, which makes it easier to fit in.

What balancing does

A wheel and tire are never perfectly even all the way around. Balancing spins the assembled wheel on a machine, finds the heavy spot and adds small weights to the rim to cancel it out. A wheel that is out of balance gives you a shake through the steering wheel or the seat, usually starting somewhere around highway speed on the 417.

An off rim change includes balancing, because a tire that has just been mounted needs it. An on rim swap doesn’t, because those wheels were balanced when the tires went on. They can drift out over time, though. Weights fall off, rims get knocked out of round in potholes, and tires that sat all summer can develop a flat spot that takes a few kilometres to settle. If the car shakes after a swap, tell us and we’ll check the balance.

Tire pressure sensors

Most newer cars have a tire pressure monitoring system, and on many of them it uses a small sensor inside each wheel, built onto the valve stem. That matters as soon as you own two sets of wheels.

You have two choices with a winter set. Fit sensors to the winter rims, so the system keeps working all year, or run the winter wheels without them and live with a warning light on the dash until April. The car still drives the same, but it can no longer tell you about a slow leak, and a slow leak in January is the one you want to hear about.

New sensors usually need to be introduced to the car. On some models that happens by itself after a short drive. Others need a scan tool to program them, or a relearn procedure through the dash. We tell you which kind your car has before ordering anything.

On an off rim change, the sensor stays in the rim, and the tire has to be broken down around it with care. The sensor batteries are sealed in and don’t last forever, and the metal valve stems on some sensors corrode in salt. If one is failing, you would rather find out with the tire off than after it is mounted.

Storage, and the other questions

People often ask where to keep the off season set and what it costs.

If your car has locking wheel nuts, leave the key in the cup holder or the glovebox. Without it, the wheels can’t come off. After any wheel change, it is a good idea to have the nuts checked again after the first hundred kilometres or so, since alloy wheels in particular can settle.

Booking the swap

Book online and pick either the on rim or the off rim tire change, so the right amount of time is held for your car. Put the other set in the trunk or the back seat, and drop the car off by 9am. We call when it is done. The shop is open Saturday 8am to 3pm, which is when a lot of people prefer to do the seasonal swap.

While the wheels are off is the easiest time to look at the brakes, so if you have noticed any noise, say so in the notes and read about our brake repair. If the car shakes even with balanced wheels, or pulls to one side, the cause may be a worn part in the suspension and steering. The tire change page has the rest of the details.