Can Tires Be Shaved For Autocross / Track Use / Competition?

One of the reasons radial racing slicks are so effective is they feature shallow tread depths, and their contact patch acts as a single unit. However, any tread design that breaks up the contact patch into smaller elements or adds additional tread depth (required to enhance wet traction) will increase tread block squirm and reduce dry performance. This means that tires typically provide their worst wet traction and their best dry performance just before they wear out. It's also important to remember that the heat generated every time a tire is driven activates bonding agents in the rubber. As this process is repeated continually throughout the tire's life, its rubber compounds gradually harden and lose flexibility, reducing the tire's grip. Therefore, a shaved new tire will provide more traction than a tire worn to the exact same tread depth after being driven for thousands of miles on the road.

Tire shaving is an effective means of permitting more of a tire's performance capability to be realized early in its life. And in many cases, shaved tires used in competition actually have a longer useful life than tires that enter competition at full tread depth.

The process removes tread rubber and reduces tire weight by several pounds. A shaved tire's tread profile will usually result in a slight increase in the width of the tire's contact patch, putting a little more rubber on the road. The resulting shallower tread depths reduce the tire's slip angle, increasing its responsiveness and cornering power by minimizing tread block squirm.

Minimizing tread block squirm also reduces heat buildup and the risk of making the tire go "off" by overheating its tread compound. Depending on the severity of overheating, the overworked areas of the tread compound may turn blue, tear, blister or chunk.

So with all of these benefits, the next important questions are: "Which tires need to be shaved?" and "How far should they be shaved?"

Extreme Performance, Max Performance and Ultra High Performance Summer Tires

Since they are not purpose-built for track use, most of these tires begin with 10/32" of starting tread depth. Our experience is that shaving them to no more than 6/32" of remaining tread depth will provide a noticeable improvement, while shaving them to approximately 4/32" will allow them to run even faster lap times. However, in all cases, tread temperatures should be carefully monitored to assure they don't exceed 210° Fahrenheit and that there is relatively even temperature distribution and wear across each tire's footprint to reduce the risk of overheating or blistering the tread compound.

It's also important to remember that once used, all tires will be a little less effective during the next competition season. Therefore, we recommend that tires be shaved to a depth that is sufficient to last for no more than one competition season. If it is very important to you to do well in the one event you run a year, running tires shaved to about 4/32" will further enhance your performance.

Track and Competition DOT Tires

The following tires are manufactured with only 4/32" to 4.5/32" of molded tread depth and do not require tire shaving for autocross or track use.

• BFGoodrich g-Force R1
• BFGoodrich g-Force R1-S
• Hankook Ventus Z214
• Hoosier A7 Radial
• Hoosier R7 Radial
• Toyo Proxes RR

Most other Track & Competition DOT tires begin with 6/32" to 8/32" of molded tread depth and typically do not require shaving for autocross use, driver's schools, track days and competitive track use in dry conditions. Shaving these types of tires may offer a slight improvement in initial lap times, but will result in a commensurate reduction of tread life.

Tire shaving is a manual process performed by a skilled individual. Though the shaving occurs on a rotating machine comparable to a lathe, the variable runout characteristics of tires combined with the slight inconsistencies inherent to any hand-performed operation creates the possibility for small deviations from the targeted tread depth. Because of this, Tire Rack allows a tolerance of plus or minus 1/32" from the requested tread depth measurement.