Motorcycle Maintenance

Tire Wear And Replacement | Ask the Geek

Wait, there's still plenty of tread left on the sides...

Sport Rider

Wait, there’s still plenty of tread left on the sides…

I have been riding at a couple of trackdays this summer, and I had a question about tire wear. If I keep doing trackdays, should I be able to run my tires right down to the wear bars before replacing them? I have been using Michelin Pilot SuperSport tires, and I ride in the intermediate group. Various people have said that I will only be able to do two or three days on a set, while others have said I will have to change them when they are halfway to the wear bars. How many days should I expect to get out of a set?
Bill Churchill
London, ON

There are many factors that determine tire wear on the racetrack, making any hard-and-fast rule for replacement intervals almost impossible. Your riding level, the weather conditions, the track surface, and the tire itself all factor in to how long a tire will last at the track. A novice rider on street tires might go a dozen trackdays and be able to wear tires right down to the wear bars without noticing any change in performance, whereas some top-level racers will not use a tire with more than one tire-warmer heat cycle on it—even if it hasn’t actually been used.

In general, tires nearer the street end of the spectrum are less affected by heat cycles, and it’s more about the actual wear of the tire. Used on tracks that are not overly abrasive and in moderate temperatures, and at a pace that doesn’t overheat the tires, a street-based tire will go multiple trackdays with little or no degradation in performance. When I instructed at Jason Pridmore’s Star Motorcycle School, we would routinely go several hundred track miles before changing the instructor bikes’ Dunlop Sportmax Qualifiers with no issues.

DOT-race tires are definitely stickier and give better performance but will perform at their best for just a single session or race at the track; grip degrades significantly with each heat cycle, and actual wear can be noticeable in less than a dozen laps at a trackday under moderate-to-hard use. This is partly why we have never recommended DOT-race tires for trackday use: Sure, they work great for the first session, but then it’s all downhill from there, especially at a hot, abrasive track.

Street/track tires like the Michelin Pilot SuperSport tires you are currently using (Michelin says the SuperSports are intended for 50 percent street and 50 percent track use) are constructed to straddle the middle ground here. They are typically able to withstand multiple heat cycles and trade off some of a street tire’s durability for improved grip at the track. While you will definitely get more than a single session out of a street/track tire, how much more begins to depend on those other factors: On a hot day in Southern California at a grippy track, an expert-level rider could see significant wear over a single trackday, notice a definite decrease in handling performance, and choose to mount a new set for every trackday. Riders at the intermediate or novice level, riding in conditions that don’t tax the tires, could go as many as several trackdays without noticing any drop in performance from a street/track tire.

A couple of other considerations about tire replacement intervals: If you are riding on worn tires or even worried that your tires are past their prime, it will take away from what you are trying to do at a trackday—work on your riding. Fresh tires will give you confidence to push yourself to your own limits rather than the tires’ limits and focus completely on your riding. And as we’ve stressed before, it also comes down to your budget and what the peace of mind from new tires means to you. Is it worth risking a fall just to eke out another trackday from a set of tires to save a few bucks?

All that is a long-winded way to get to this: When to change your SuperSports is really a matter of their performance over time and your confidence in them rather than the actual wear, provided they have sufficient tread and the rubber itself is not visibly deteriorated or shows abnormal wear. Given your intermediate level of riding, I would suspect that you will experience that drop in performance and your confidence in the tires or see that visible deterioration before you get down to the wear bars, and that will be the sign to replace your tires.

Got a question for the Geek? Send him an email: srmail@bonniercorp.com