The Temporary Spare Tire

I have been noticing many cars driving down the road with the temporary spare tire or “donut” as some people call them. The spare tire diameter is smaller than the existing tire size. The reason for this is they don’t take up much space and the smaller tire weighs less than a full-size one.

Many of today’s cars don’t even have a spare tire; they come with a fix-a-flat type of kit only. If your car has an actual spare tire, it is only to be used as a temporary fix (that it what the “T” means in front of the tire size on the side wall), not exceeding 45 MPH in speed and to get you to the nearest repair shop.

I am amazed when I see a car on the freeway moving at 65 MPH plus on a temporary spare tire. Earlier I mentioned the temporary spare tire is a smaller diameter. This fact is important because if the spare is placed on a drive wheel, (on the front of a front-wheel drive, or on the rear of a rear-wheel drive car) it is even more critical to replace it as quickly as possible.

Different size tires from side-to-side on any car’s drive axle will damage the transmission/transaxle on a front drive or the differential assembly on a rear drive of the car. Never use a smaller temporary spare tire if you drive an all-wheel drive as this will damage the drivetrain unit that controls the all-wheel drive.

Tire issues never happen at a convenient time, so please check the air pressure and tread wear regularly. You can save yourself time and money while lengthening the life of your tires.