Tire compound selection, sizing and grooving are a few areas that can make you better than your competition, let’s first explore tire compounds.
Tire Compounds - This is one area that can make or break your night. You can have a good handling car all night and the wrong compound will make for an ill handling feature car. We use Hoosier tires for a variety of reasons such as compound selection, sizing, construction of the tire and how they adhere to the track. We feel Hoosier Tire offers a better variety of options in these categories when compared to other tire manufacturers.
The compound scale for Hoosier tires is as follows: a D10 being the softest followed respectively by a RD12, D12, RD15, D20, D25, D30 and a D35 is the hardest compound available to 600 competitors.
In 600 micro sprint racing, both rear tires can need a compound change. By this I mean in the 270’s, usually you can run the same compound on the left rear all night long. However with a 600, suppose a track starts to get abrasive and dry and the right rear tire you were using in the heat race was a Hoosier 69x10x10w-RD12 and you decide to go with a 69x10x10w-D20 for the feature, most of the time in this situation you would use a D20 on the left rear as well. The point being, don’t forget the left rear tire too.
We usually will run a 63 or 64 inch tire on the left rear. My team will start the hot lap session with a 63x10x10-RD12 and a 69x10x10w-RD 12 on the right rear. There are a few tracks that stay wet and tacky and you can use a D10 on the LR and a D10 on the RR as well. However, the RD12’s are soft enough to start on a tacky race track and provide more durability if the track you are competing at tends to get harder. This in turn can provide you with longer tire life as opposed to using a softer compound earlier in the night.
The following is a list of things to look for during the night that might merit a compound change:
- Watch the color of the track as the night progresses - dark brown or wet to start and lighter brown as the track dries out and the evening progresses.
- Pay attention to the racing groove - find out where most of the cars are running on the track.
- Look from the bottom of the track to the top - the top of the track is where you can sometimes pick up some spots on restarts. Most race car drivers don’t use the top of the track because this requires a lot of confidence in your driving abilities and a good handling race car. Tire compound can be a contributing factor in both instances.
- Watch other heat races - how the dust is coming off of the rear tires, it also helps if you look at tire wear of your fellow competitors. Look at the tire and see if the tire they have a grained texture. Look for a lip on the blocks of the tires and also look to see if the lip is on the font of the block, on the outside of the block or on the rear of the block. This can tell you if that particular car was getting good side or forward bite.
When selecting a compound for the feature, your starting position can play a big role in what compound you may select. If you start in the first two rows you might want to think about a softer compound. This will enable the car to take off quicker, and can put you out front. Once you are out front you can pace yourself to take care of your tires. If your car goes away as the race progresses, you can adjust the car with shocks or wing adjustments to compensate. If you choose this route you can also close up on the stagger a little more because your car will probably free up at the end. If you choose to set the car up for the end of the race, then a harder compound is the way to go. Be careful when doing so because the early part of the feature is so important and you don’t want to loose track position because your tires are not up to operating temperature and your car is not getting any bite.
The ‘Art’ of Stagger - We like to take the approach of breaking down the night from hot laps to heat race and then heat race to feature. My team will usually start with more stagger for hot laps to keep the car ‘freed up or loose’ and use this as a starting point for the night. Typically we reduce the stagger as the night progresses. A majority of the time we reduce the stagger about 1 to 1 1/2 inches. For example, at a given track we will start with about 6 1/2 inches of stagger for hot laps and reduce the stagger to about 5 to 5 1/2 inches of stagger by the end of the night. Don’t be easily fooled by track conditions or force yourself into changes. Early in the year when tracks still have bite, we tend to keep the stagger the same all night and if we have to change stagger, we will only change about ¼ to ½ inch. Also be aware that stagger selection can vary from one chassis manufacturer to another, the best thing for you to do is to contact your chassis builder and discuss what they recommend.
In some instances, depending on track conditions we like to leave the stagger the same as the heat race and set our chassis to the tight side with adjustments like RR wheel offset on the axle, wing angle and shocks. If you choose this route, grooving or siping is an option that will help your tires come in quicker.
Grooving & Siping – First let’s distinguish between the two; ‘Siping’ a tire is done by putting small ‘razor’ size slits in the tread pattern of the tire. ‘Grooving’ or ‘Cutting’ a tire is actually adding grooves to the already established tread pattern of the tire.
Siping a tire helps build heat quicker and a it also helps dissipate heat at the same time when the tire gets to operating temperature and the sipes open up. Never sipe a tire more than half the depth of the tread block, any deeper and this may cause the tire to tear or ripe apart. As a rule of thumb, we normally only sipe harder compound tires, we find that there is not much benefit to siping softer compound tires.
When using different grooving and siping patterns consult Hoosiertire.com. When on the site click on the “track dirt” section. When in that section click onto “FAQ”, refer to Question #8. This will prove to be a very good source of information for you and your race team.
I hope this article gave you some useful insight. In weeks to come, I will be contributing an article on chassis. The 600cc micro community is very lucky to have a web source like 600Scene.com. I feel this will prove to be useful source for news and information on 600 micro sprint racing throughout the country. Brett Schoenly and Schoenly Enterprises would like to wish Kevin and Dillon good fortune on their new venture. Good luck to everyone in 2006 and see you at the races!
