Big-time racers will always...
Big-time racers will always cut their tires for maximum immediate performance, but if you are trying to stretch your racing dollars, it is possible to groove and sipe your tires in a manner that actually increases their usable lifespan. Jeff Huneycutt
They say you can't have your cake and eat it too. Sometimes that's true, but there are times when you really can have both. We recently sat down with Weir Schankel of Van Alstine Manufacturing. Van Alstine produces tools to help maintain and modify tires, and its grooving and siping products are very popular among racers. Because of its relationship with several of the top racers in the nation, Schankel has worked with many of these racers on developing their tire programs.
When it comes to grooving and siping, many automatically think of cutting up a tire to within an inch of its life in order to get maximum performance for one race, or sometimes two. But Schankel says that with intelligent use of the grooving and siping tools you can actually prolong the useful life of a dirt race tire while also maintaining a good competitive level. In other words, at least when it comes to tires in dirt racing, you can sometimes have your cake and eat it too.
"The key," Schankel says, "is these tips are for racers who are racing as an avocation, not a vocation. These tips will definitely help you get more useful life out of your race tires, but they aren't going to help you get to that absolute bleeding edge of performance. This is for guys who want to use their tires several times before they are forced to discard them. If you aren't racing for a living and are struggling to make ends meet, these may be very helpful to you. But if you are racing for a living and willing to do whatever it takes for those wins, then you might want to follow a different tactic."
A grooving tool, like this...
A grooving tool, like this one from Van Alstine, uses a thin blade that is heated by an electric current so that it actually melts its way through the rubber of the tire. This makes the process of cutting grooves into a set of tires a whole lot easier. Van Alstine
Of course, tires are always one of the biggest expenses for any Dirt Late Model race team, and given the current economic climate, we suspect that there are going to be more and more racers willing to give up a little bit in terms of speed if that means the opportunity to make it to the track for another weekend.
Conceivably, these tips can help you produce a better finish if the dollars you saved from stretching your tire budget can be put toward something else on your car-or even your fuel bill to get to the racetrack. Obviously, most of the tips here are for dirt racing classes where cutting and siping your tires are legal, but even if you race in a class where they aren't legal, we still have a useful tip for you.
RegroovingGrooves are the large cuts in the tire that create the tread pattern. Siping-which we will get to later-creates the small slits cut into the rubber which may be practically invisible at a glance. The point of grooving a tire is to create edges. It is the edges of the grooves that bite into the dirt surface of the racetrack and give you much of your available traction, especially when the track is wet.
By using a variety of blades,...
By using a variety of blades, you can cut different size grooves easily. This allows you to widen a groove to get a fresh edge without cutting any deeper. Van Alstine
The problem is that as your rear tires accumulate laps the rubber outer surface of the tires wear and the edges of your grooves become rounded off. The rounded edges offer less "bite" into the track and traction slowly fades.
"What guys are doing after a race is to go in and cut the existing grooves wider to give them a fresh, new edge," Schankel explains. "When you are regrooving a tire, you really don't want to cut any deeper than the original groove than necessary. You certainly don't want to get down to the tire's casing; you always want to leave some rubber covering.
"So if you are recutting a tire, you want to remember that you aren't so much cutting to deepen the groove-although you are doing that a little bit-you are cutting to sharpen up those edges. So what you want to do is set up your tire grooving tool so that while you may be undercutting your groove a little bit, what you are mainly doing is sharpening up that leading edge.
Siping tools use a series...
Siping tools use a series of razor blades to cut slits into a tire. Properly siping a tire can require hundreds of cuts. As you can see here, multiple blades mounted into the siper allow multiple cuts in one pass, which greatly reduces the amount of time required to completely sipe a tire. Van Alstine
"One trick some racers have discovered to make this a little easier," he continues, "is to make your uts with two different blades. The first time around they will groove their tires with a round-bottom blade, maybe a 1/8-inch blade. Then, after their tires have worn and they decide to regroove, they will come in with a No. 5 flat-bottom blade. Now, the No. 5 is a little bit wider, so you are straddling that groove to give you a fresh edge. And it's not really cutting any deeper because the first time around you were cutting with a round bottom, so the flat-bottom blade doesn't cut much deeper, but it does cut more on the sides of the groove to sharpen up the edges."
Extra Grooves
If you are planning from the beginning to get all the use out of a set of tires you can get, you can plan ahead when grooving your tires. Instead of completely cutting up a new set of tires, Schankel says you can leave room to cut in a new set of grooves later on. Then, when the tire becomes worn and begins losing traction, you can go back in and cut additional grooves.
By having fewer grooves than the competition, you will have to face the fact that you may be giving up some performance in the early life of the tire. But if your goal is to maximize your track time and not necessarily to win every race, this may not be a problem for you. Just make sure not to cut your grooves too close together or your tire might start "chunking" or tearing apart on the racetrack. Unfortunately, we cannot tell you exactly how close "too close" is because it varies greatly depending on the softness and composition of the tire, your car's power and setup, and even the track itself.
Flip Them
The greatest wear on the grooves in your tires will be from trying to accelerate the car. Braking will also wear the grooves, but not nearly as much. This means that with some tread patterns you can flip the tires around and use the back of the groove to provide a fresh edge. If you are running the same wheel offsets you can probably switch the left-side tires to the right and vice-versa. This may help you get an extra run out of a set of rear tires before having to regroove them.
Siping
Siping is the process of cutting slits in the tread of your race tires. Sipes serve several purposes, some of which help improve traction while others help improve tire durability. Siping is definitely a labor-intensive process, but it is quite helpful when allowed by the rules.
Most sipers depend on the...
Most sipers depend on the sharpness of the razor blades to cut through the tires. But this siper from Van Alstine actually heats the blades a lot like a grooving tool to eliminate the need to constantly replace dulled blades. Van Alstine
"Siping has a few advantages," Schankel says. "First, it gives you extra edges which helps traction, but the slits also make a hard tire act softer. The slits also help a tire heat up quicker so you reach optimum traction sooner. The heat builds up when the sides of the slits work against each other. But after the tires have heated up, those sipes will open up and allow the tires to cool down. They also keep the tire from getting too hot. A tire that gets too hot will glaze over, and you don't want that. So siping your race tires will not only help improve performance, but should also help a tire last.
"As a general rule, you usually only want to cut your sipes about 1/16-inch deep. If you sipe deeper than that you might see some of the rubber ripping out. But then again, conditions will change the best depth for cutting your sipes. Sometimes you may need them deeper, sometimes shallower." Try asking around at your racetrack to see what works best for other racers and then experimenting a little on your own.
Sanding Or Grinding
In many lower-level Dirt Late Model racing classes, the rulebook prohibits any kind of cutting on your tires. This includes both grooving and siping. If you are willing to bend the rules, it is conceivable that you could regroove a used set of tires to get a fresh edge, but the reality is that it is very hard to regroove a tire so perfectly that it wouldn't be noticeable.
Instead, if you are trying to make your tires last as long as possible and your rules prohibit cutting, you can break out the power sander. Using a light-grit sandpaper, use the sander to lightly go across the top of the tire to knock down the rolled edges off of your grooves. Make sure to sand the entire tire evenly so that you do not create an unbalanced condition or cut waves into your tire. Done correctly, your work should be hardly noticeable (even though few rulebooks specifically prohibit this since sanding is often necessary to knock the glaze off of a tire). Sand off just enough to restore the edges of your grooves, and you are good to go.