Tire Sizing and Wheel Spacing

One of the major questions we get here at Deals on Wheels concerns tire sizing and wheel spacing. These are important elements in choosing just the right wheels and tires for your ride. The Uniform Tire Quality Grade (UTQG) provides ratings for traction, tread wear, and temperature resistance. This can help an individual decide on the best tires for their particular usage and driving habits.

Tire Example: P205 65 R16

Tire Sizing (Metric)

Tire Class – “P”

Those first letters tell you the tire’s class. In this example, a “P” indicates passenger car tire. If there’s no letter before the size then this means it’s a European metric tire. An “LT” designates light truck tire.

Section Width – “215”

Millimeters are used to measure a metric tire’s section width. Measuring is done from sidewall to sidewall. In the above example, the section width of the tire is 215mm.

Aspect Ratio – “85”

This number describes the height of the sidewall and is a percentage of the section width. For example, 85 percent of the section width of 215mm would equal 182.75.

Tire Construction – “R”

An “R” is commonly found here and it indicates radial tire construction.

Wheel Diameter – “16”

This indicates the wheel diameter in inches.

So in the above example, you have a passenger tire that is 215 mm wide with radial construction.

Wheels

Selecting the right wheels to go with your tires is also important. Today many drivers are choosing over-sized wheels or tires to make a strong statement and give their auto a totally different look and feel. However, if you purchase a tire that’s too narrow or a wheel that’s too large, you can lose handling and cornering ability. Be sure to discuss your needs and wants with one of our tire sizing and wheel spacing experts so that we can help you find the right combination for your driving needs.

Below we explain wheel spacing:

Wheel Width: This is the distance between the inside flanges rounded to the nearest 1/2″. Since all tire sizes have minimum and maximum wheel width limits, you will need to figure a wheel width that will work with your tire size.

 Wheel Diameter: This is the distance from bead seat to bead seat across the diameter of a wheel and it must be exactly the same as the tire rim diameter. Match the wheel diameter exactly to that of the tire.

 Wheel Offset: Distance between wheel mounting surface where bolted to hub of drum and centerline of rim. This determines your vehicle’s “tracking” or distance between tires on each axle. It’s important to keep the wheel offsets as close to original as possible. Otherwise you may encounter steering difficulties or wheel bearing fatigue.