Spec Tire Race-Preparation
From Nexus Racing
Over the past few years, spec tire electric racing (using pre-mounted tires) has become very common in the USA and around the world. When you enter a big event or competitive racing environment that uses a spec tire, however, tire preparation is still very important.
While you no longer have to (or are allowed to) experiment with the tire compound, insert, air gap, and wheel stiffness of your tire sets, you do need to undergo certain tasks if you want to ensure that your first one or two runs with each set are as fast as possible. Here, we will cover the things you should do after opening the tire set, but before applying traction compound or warming.
Just keep in mind that even though your touring car will usually handle better with a fresh set of tires, even pre-mounted tires may not run at their full potential straight out of the package.
Removing the tire seams leftover from production:
All rubber tires for touring cars will have a noticeable seam down the center that is leftover from when they were produced. If the seam is large enough, it can have negative handling effects on your car. In the worst-case-scenario, the seam could cause your car to break traction early in the race, which hurts some of your early lap times and adds unnecessary heat to your tires (which will hurt some of your later lap times).
The idea behind removing the seams is to ensure that the tires have the largest possible amount of contact with the racing surface:
The simplest and most economical way to remove a tire seam is to sand it off using a rotary tool (such as a Dremel tool) with a sanding drum attached. All you have to do is carefully hold the tool at an angle to the seam (to avoid removing rubber from the area around the seam) and sand the seam away. While this method is simple and cheap to most racers, it is certainly the most tedious.
Another method of removing the seam is to cut it off using a small, sharp parts nipper. While also convenient to some racers, this method can also be tedious. It is best to have a nice, sharp pair of nippers to make this method quick, easy, and effective.
The most popular method of removing the seam involves using a tire-sander or low-rpm tire truer to spin the tire while you hold either sandpaper or a file against the seam. This method is much more convenient if you regularly remove the seams from your tires. We recommend using either a narrow file or some medium-fine grit sandpaper:
Nexus Racing Tip: Clamp a standard tire truing arbor to a pinion gear of the proper size to create a small, portable tire sander:
When removing the seams from your tires, the key thing to remember is that you should not remove too much rubber. The seam should still be slightly noticeable when you are finished, but it should not be prominently sticking out from the tire.
Re-gluing the tires:
Is there really any point to re-gluing your (pre-glued) spec tires? Absolutely!
There are two noteworthy reasons for re-gluing your tires in a competitive racing environment:
The first (and most obvious) reason is for insurance. Though the few companies that market pre-mounted tires take much pride in their quality control, you can never be totally sure that the tires are fully glued. Also, you can never be certain that the tires were not exposed to extreme temperatures (high heat or cold that can loosen the bond of the glue) as they made it through distribution, hobby shops, etc.
The second reason to re-glue is to ensure that the tires run as "true" as possible. If small areas of the tire bead are not glued tightly to the rim, these areas can expand away from the wheel as you run the car on the track, causing the tire to not be as round (especially at high speeds).
Re-gluing pre-glued tires can seem like overkill. Sometimes, however, racers make big sacrifices (financial or other) to attend a racing event. In these situations, it is certainly worth few minutes of your time to ensure that your tires do not hold you back.
Process for re-gluing each side of each tire:
First, clean the seam between the tire and rim with a good cleaner such as rubbing alcohol or motor spray. This will remove any oils on the sidewall that are leftover from packaging, etc, so that the CA glue can make a good bond with the tire and wheel.
CA glue selection: It is best to choose a thin CA glue that is:
-specialized for RC tires (such as Pro-line and Team Losi glues)
-relatively fresh (If your glue is turning excessively white in color as it dries, it will have a brittle bond, making it NOT suitable for gluing tires.)
Next, apply thin CA glue around the seam. Quickly after applying the glue, pull the sidewall away from the wheel slightly (to allow the glue to flow into all "vulnerable" crevices around the bead) and then push the sidewalls back inwards towards the wheel for several seconds while the glue dries. This process allows you to get the tightest bond possible.
If you are using relatively fresh thin glue as recommended, the glue should set quickly as you push inwards. If it doesn?t, you can place a thick rubber band around the tire to keep the seam tight while the glue dries.
Most racing events that use handout or control spec tires will limit the amount of sets that each driver can race. In these situations, it is useful to label all of your tires so that you can distinguish both from set to set and from tire to tire within a set (i.e. left or right and front or rear tire).
When you are getting only 1-3 "fast" runs out of each tire set (the first run usually the fastest), it is useful to know the following information about each tire:
Which set is it from and how many runs does it have?
This is pretty self explanatory; since typical spec tires will deteriorate in performance the more they are run, it is ideal to keep your tires grouped so that you are able to determine how many runs each tire has.
On which corner of the car was the tire run?
When using spec rubber tires for a limited number of runs, it is especially important to specify each tire as a "right" or ?left? and consistently run the tire on this particular side in later runs. This is important because each tire will "scuff" itself for moving in the forward direction from either the left or right side when run for the first time. If you run the tire on a different side in the next race, the tire will run "loose" for several laps because it was already scuffed for going in the opposite direction. Subsequently, as the tires run loose early in the race, they will likely overheat, which can both cause your car to run loose for the entirety of the race and add excessive wear to the tires.
As a result, it is not recommended to rotate your tires from left to right over the course of an event.
Tire Strategy Tip:
Rotating your rear tires to the front of your car (and installing fresh tires on the rear), on the other hand, can be a beneficial tire strategy over the course of a racing event. This combination will usually run better than if you have a pair of used tires on both the front and rear. In many situations, this tire strategy will allow you to have a consistent-handling car from run to run. All in all, whether or not this strategy would benefit you depends both on the number of tire sets that you are allowed to race and the type of tire used.
In this situation, it is again beneficial to label your tire sets, because you still need to know which tires came from which sets so that you do not install the wrong combination on your car.
Labeling the tires:
Basically, you can come up with your own system for labeling your tires. For example, the phrase "2-RF" could represent the right-front tire of your second tire set.
The "industrial" or "professional" versions of the Sharpie permanent marker are great for labeling your tires, as they are more resistant than other permanent markers to the types of cleaners and traction compounds used in RC racing.
One final note about preparing your spec tires:
Sometimes, no matter how much effort you put into preparing the tires before you install them on your car, you will need to give your tires a quick "scuff" before the race while your car is on the line. Whether or not (or how much) you will need to do this depends on how your car is set up. When it is necessary to scuff at the line, it is best to ensure that you only scuff the tires in the "forward" direction (in other words, scuffing the tires by doing donuts at the starting line can do much more harm than good).
There you have it! After completing these procedures, you will have organized spec tire sets that are "able" to run at their full potential. Now, keep in mind that your use of different traction compounds and warming methods will also greatly affect the performance of your tires. In fact, these extra procedures become even more important when everyone is running the same tires!