“Minus One” and “Minus Two” Conversions

For cars with low profile tires, it is often a good idea to downsize the diameter of the wheels by an inch or two when the time comes to fit winter tires. Low profile winter tires are not only hard to find and expensive, they’re also less effective and facilitate the buildup of snow inside the wheels.

Wheels of a smaller diameter should always be shod with taller (higher profile) tires to keep the rolling diameter, the diameter of the wheel / tire combination, constant for the following reasons:

  • to allow the speedometer and odometer readings to remain accurate;
  • to prevent the engine from running at too high an RPM at a given speed;
  • to ensure that suspension operation is not adversely affected.

Making a “minus one” conversion means fitting a one inch smaller wheel with a suitably higher profile tire to keep the correct rolling diameter, while a “minus two” conversion involves a two inch smaller wheel with an even higher profile tire.

One clue: the easiest way to fit smaller winter wheels to your car is to go to the smallest (usually the standard) wheel offered by the manufacturer as original equipment for your vehicle.

Important note

Making a “minus one” or “minus two” conversion is not to be taken lightly.

You should consult a specialist and / or your dealership before fitting wheels or tires of a different size to your car. Also, you should always follow the recommendations made by the manufacturer of your car.

Fitting improper wheels to your automobile could cause mechanical problems and could result in an accident.

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