Guide to dual-purpose tires Montana

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Race compound tires often carry the R designation in the name of the tire (such as A032R, 555R, R3SO3, or RA1) or may simply be so designated by the manufacturer without any R used in the name (V700). Unfortunately, there is no clear way of knowing if the R on the sidewall refers to the compound or the radial carcass, since almost all radial tires also have an R on the sidewall. If in doubt, you just have to do a little extra research on the tire, or consult with your tire retailer.

Dual-purpose types

Dual-purpose tires are available with either

Full tread for street driving and wet racetracks

Shaved tread for dry racetracks

Shaved tires aren’t welcome everywhere:

Shaved tires may be illegal and unsafe for street driving.

If you have shaved tires for racing, make sure they are legal for
your class.

Dual-purpose tires, like the Yokohama A032R (see Figure 5-6), are often designed as wet-weather race tires. Dual-purpose tires use racing tire rubber compounds on a reinforced street-legal carcass. Sturdy, heavy sidewalls can easily offset any weight saved from ultra light alloy wheels, so consider the big picture before settling on a setup.

I’ve run Yokohama A032R dual-purpose tires on my MR2 for three years, and they’ve served me well as a compromise tire for driving to a weekend track day, coping well with the rigors of track use, and still allowing me to drive my car home after the event without changing wheels. A set lasts me about 5,000 miles before they become either too worn and/or heat cycled. Companies like Toyo, Bridgestone, and Kumho offer similar tires. For the drag race fans, Nitto’s 555R can be dropped in pressure so it reacts much like a “wrinkle wall” drag tire on launch; at normal inflation, it corners with the best.

Things to consider

Although I personally run my daily driver on dual-purpose street tires, there are a couple of significant considerations to keep in mind before running out and buying a set:

These tires usually last less than 7,500 miles on the street before the tread wears below legal and safe depth, or they become hardened from multiple heat cycles.

They can be much noisier than normal street tires, much like I imagine monster truck tires would sound at freeway speeds.

Most dual-purpose tires are designed for racing and autocross classes that require street-legal tires. They’re also great for track days.

Proper tire treatment

Top competitors in street tire classes treat their tires like racing tires. If they drive the car on the street, they don’t use their competition tires. If you have dual-purpose tires for competition or track days, I recommend that you

Minimize the street miles on the tires.

Complete at least one full heat cycle before driving hard on the track.

Use shaved tread if the tires are to be driven only on dry racetracks.
(Make sure the shaved tread is legal for your class.)

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For Dummies is a registered trademark of Wiley Publishing, Inc. in the United States and other countries. Used here by license.