How do you choose the right tire? This is a very common question and one you can ask 10 times and likely get 10 different answers. If I’m travelling to a race or track I’ve never been to before I start looking at the following:
1. Find some good pictures or better yet, video of the track with cars running on it.
2. Ask either some locals or teammates that have been to the track
3. Keep an open mind about the surface going into the race.
When I’m looking at a surface I’m looking at a few factors for example; moisture, color, indoors or outdoors, temperature. Moisture and temperature often affect one another. The damper the track, generally the cooler the surface can be. Note however that at an outdoor race for longer mains the track maybe watered early on, but dry out later in a longer main so consider that factor.
The color of the dirt can help in the fact that if the dirt grooves up and gets black or blue hues to it, this is helpful to know since rubber is staying in the track where as some soils do not accept it. Traction is often different in this “line” than it is outside the line. The wider the groove, the more this is important in your tire compound choice.
Indoor tracks generally don’t get much warmer than the ambient air temp so you can often get away with a softer compound without the penalty of wear. A track that is outdoors may see a 40+ degree swing in track surface temperature from the morning to the afternoon. Early morning you may run super soft or soft, but change to soft or medium soft in the hotter parts of the day.
The texture of the surface must also be considered. Tracks which develope big ruts and sharp edged holes can change your tire choice slightly. Smaller pin tires generally are less grabby going through that type of terrain and are “safer” for lap times. The DNC this year was hard packed, dusty, and had sharp acceleration ruts out of most turns. This meant most guys were going to small to medium pin tires. They also qualified on different compounds in the day versus the later evening runs under the lights. A super smooth track will likely also be ran on a low pin tire but a “Web” style tire may prove quickest if there’s little to no dust.
Tread height and density is always something to consider. Taller pins can get past the dust and dig into the hard part of the track. This can be a downside however if the tread height and tread compound combination is too soft. When this occurs the tread can collapse or fold over making for a condition where the tire “squirms” and causes very erratic handling. A tire with more “void” between the tread helps in self cleaning and excels in loam or heavy dusty tracks. The closer the tread density the less dust the tire can displace but the better resistance to “squirm” the tire will have. I look at it this way; each little pin offers an “edge” for traction. The more “edges” have to grab the track the better as long as I can get past the dust and loam to get that tire/pin into contact with the main racing surface. Dust is like water on pavement, you wan to manage it as much as possible allowing the main tread to get in touch/contact with the main racing surface. This is also why a lower pin/tread height is ideal on a clay surface. In this condition there is little to no “dust” to prevent the tire from reaching the racing surface. In this condition the tread or in case of slicks make traction from the friction of the rubber alone on the surface. This can be a fine line to walk if the racing line is very narrow and outside that line marbles make passing nearly impossible. In those cases I often elect for “ghost pins” or “stripes” where the tread is visible on the tire but is very very low, or in the case of stripes the center of the tire is a slick but outer edges carry tread to handle the times where deviating from the “groove” line is necessary.
Going into the 2015 DNC I guessed at some JConcepts Double Dees in orange, JConcepts 3D’s in blue, and some JConcepts Barcodes in orange to bring with me. I had heard the track “could” groove up and knew bar codes were a safe bet for that condition. I’d also see some video where there was a very narrow groove at times, passing required you to step out of that groove which meant a small pin like the Double Dees would be ideal. I also knew that if the track maintenance was lax or not kept up the track would loam up a bit while still having a “line” in the track. This is where a multi level pin tire like the 3D’s would shine. Having spent some time on the track to practice the 3D’s felt the most consistently quick where a fast lap could be reached with the Double Dees. With only mild watering done on the track, the surface was going to be hit or miss depending on how much water was put onto the surface. Since this was outdoors no brooming was ever done so I chose to race the mains with the safe choice of the 3Ds. I managed solid 2nds in both 2wd and 4wd Pro SC this weekend.
Choosing tires isn’t an “art” or process of simply guessing. Often times the local guys have the surface down. But do NOT be afraid to go against the local “knowledge” and try something that you think will work. What works for you and your car/setup may not work for the locals or others around you. Pay attention to the tire manufacturers recommended guidelines for their rubber compounds, most if not all provide you with handy charts to help you choose the right products.
Take advantage of their information and time spent on the tracks. When in doubt, ask someone local whom you trust. Tires aren’t cheap and are in my opinion 80% of the “setup” to be fast. So take your time, choose wisely. Tires are very important and can be tough to make a choice on. Choosing tires takes time to get good at and even then, it’s never 100%. If you want my opinion on tire ideas for your local track, share the picture of video info on my Randy Pike RC Facebook page and I’ll do my best to chime in and help.
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