As autocrossers, we have a number of choices to make. While the novice autocrosser generally starts with the car they have, an early consideration is tires. Tires are a relatively easy part to change, so upgrading to “slicks” may appeal as a way to improve your car and gain time early on. Yes, I say “slicks” – the tires I’m referring to are R-compound (racing) tires that have almost no tread. These tires are DOT approved, and because of that they have two thin lines that are the “tread” of the tires. They’re not true slicks because of those two lines, but they’re near-slicks. Two popular choices are the Hoosier A6 and Kumho V710. While these tires are DOT approved, they are not necessarily street legal. State laws may render the tires not road legal in your area.
R- compound tires provide significantly more grip than street tires, so they seem like an easy way to pick up some extra time. However, they have significant disadvantages for the novice. The most obvious disadvantage is cost. R-compounds wear quickly and frequently cost more than street legal tires for the same car. Still, for the beginning autocrosser, the more significant disadvantages relate to learning opportunities. Street tires provide a more forgiving basis for pushing the traction limits. When pushed, street tires make noise. A street tire being pushed will give a screeching sound, and when that tire is pushed beyond its limit, the sound will change. A grippier tire will make less noise than one with less grip, and the super-grippy near slick R-compounds will almost never make any noise at all. This auditory feedback can be a great tool for helping a driver learn to feel when a tire is losing grip.
Street tires are also more forgiving near their limits than R-compound tires. They’ll start to provide feedback about traction limits (both auditory and otherwise) while further from their limits. Additionally, when they lose grip, the change is less harsh so it’s easier to recover.
Sticking to street tires for a while will allow the new autocrosser a chance to learn great car control skills while keeping costs lower. The times may be slower than they would be on slicks, but learning on street tires will mean the autocrosser will be able to make better use of the more expensive tires if they later chose to switch.