If you have ever paid attention to your tires, undoubtedly you have seen a string of letters and numbers on the sidewall. If you are new to tires, you may not understand what these mean,.. you may not even realize they mean anything! Following the information below will help you decode and understand the "writing on the [side]wall". Knowing this will give you the insight you need to purchase a proper set of tires or upgrade to a larger size.

Example sidewall code: 215/60R16 85R

215: The first number in the string represents the width of the tire. The wider the tire, the better contact it will make with the ground, which will improve its performance. Of course, your wheel needs to be wide enough to accept the tire. In this example, a 215-width tire will fit nicely on a 6.5-7" wide wheel.

60: This value is the HEIGHT of the tire, measured from the rim to the tread. This is expressed as a percentage of the width, so in this case,.. 60% of 215mm. Generally, when you buy a wheel that is an inch taller, you will buy a tire that is 1 "profile" shorter. In other words, to upgrade to a 1" taller wheel in this scenario, you would be looking for a tire with a 50 profile. Also, if you upgrade to a wider tire, you may want to move a half profile to retain the original diameter of the tire/wheel combo. For example, if you were to upgrade to a 225 width tire, you may want to get a 55 profile in this case.

R: This letter represents the speed rating,.. or the maximum speed the tires can safely operate at.

Possible speed ratings:

Occasionally you will see a speed rating coupled with an R. (ie, VR). The R in this case denotes that the tire is a radial.

16: This denotes the general size of the tire. For example, this tire is made for a 16" rim and WILL not fit on anything else.

85R: The load capacity of the tire, or how much weight the tire can safely support. Remember that you won't find a tire that has a load rating as heavy as your car.. you have 4 tires supporting it(just remember that the 4 tires must support a full vehicle.. passengers, luggage, and gas)! The R after the 85 just repeats the speed rating.

The load ratings range from 71(761 pounds) to 110(2337 pounds).

Now you know how to read tires, and you should be ready to handle purchasing your own when the time comes. Just remember that everything is a trade off. If you have a performance vehicle you will want a higher speed rating,.. but you may sacrifice ride quality and tread life. If you own a luxury car,.. you will go for a tire with a softer ride that perhaps doesnt have the handling characteristics of a tire with a thinner sidewall.

If you want to upgrade your wheels for looks, you will likely buy a bigger set of wheels. In this case remember to buy a tire with a lower profile than the current one. For example, to upgrade our sample tire to a 17" version, we would be shopping for a 215/50/17 in most cases. If your car has enough clearance, and if the new wheel is wide enough, you may be able to get a 225. Also,.. in some cases a 55 profile would be a better fit. This is only a rule of thumb, and you should consult the manufacturers spec sheets to compare the OVERALL DIAMETER. You want the overall diameter to be as close as possible to your stock, or OEM, tires.

If you want to upgrade your wheels for performance, you will likely buy a smaller set of wheels. In this case, you will usually be able to fit a much wider tire increasing your contact patch and cornering ability. A 235/65/15 might be a possible performance upgrade based on our original configuration. Again, this is a rule of thumb and the width and profile you purchase ultimately depend on your cars tire clearance, and overall diamater of the cars original setup.

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