Tyre Addertive

12th Scale Tyre Additive Use
A Definitive Guide for Drivers of All LevelsBackground
On any racing car – full size or scale, the tyres represent the most important factor in determining
the handling capabilities of the car. The tyres are the only parts of the car in contact with the racing
surface and as a result all of the cornering forces, pressure and friction which combine to generate
grip are transmitted through them.
For 1/12th scale racing, the tyres play an even more significant role since they can be finely tuned to
alter the handling characteristics of the car. Both the compound and diameter can be changed as
well as the additive application procedure to create a theoretically endless list of possibilities, and an
incorrect decision relating to any one of those possibilities can have a seriously detrimental effect on
the cars performance.
After fitting tyres to your car, it is necessary to treat them with additive in order to maximise the grip
they can offer on the track. This article aims to explain what additive does, how it is applied and how
it can be used to fine tune the handling capabilities of your car.What Does Additive Do?[/center]
The basic purpose for using additive on foam rubber tyres is to clean and soften them. Most tyre
additives contain mild corrosives which literally melt the rubber in the tyre. This corrosion can be
made evident if you spill some additive on a rubber or plastic surface and leave it; after a while the
surface will become tacky and start to melt. It should be noted that transmitter cases are badly
affected by this, so a tip from a well known top driver is to not accidentally leave a wet additive
brush in your transmitter bag during a long journey back from the Euros!


You will notice at big race meetings that a dark grip line becomes visible on the track surface after a
few rounds of racing. This is basically a mixture of tyre dust and additive, which collects on the track
surface as a slimy residue. This residue allows for more effective adhesion between additive treated
tyres and the track surface; in much the same way as rubber tyres on a rubbered in tarmac track.


The tyre additives currently used for 1/12th scale racing are of the oil extracted type. The most
popular of the available ones are CS High Grip and Speedtech Foam Liquid. Both are very similar, but
it is generally regarded that using Speedtech will give the car slightly more steering than CS. In the
UK, CS seems to be the preferred choice for most drivers. Many large events such as the Worlds use
a control additive as in July of 2010, when Speedtech was used. Jack The Gripper is popular in the
US, but is not as widely used in Europe



The easiest way to apply additive is using a small brush that is 10-12mm wide. You can get them
from any craft/hobby shop, but if you’re caught short at a meeting then Action Model Centre Sell
some that are perfect for the job.
It is usual to apply additive to the whole of the rear tyres, and a proportion of the fronts. For the
fronts, start at the inside edge and work your way out. 17mm is usually a good starting point.


for each rear tyre is usually plenty, and about half a brush full for the fronts. Do ensure that you get
an even coating to allow it to soak in to the foam properly. Over application of additive leads to the
tyres softening too much and going gummy with time. Tyres like this aren’t really much use to
anyone as they are inconsistent and more prone to chunking. If you apply additive sparingly, then
your tyres will last longer and you’ll get more useful runs out of them.


One of the most important aspects of additive use is that you thoroughly dry off the excess before
putting your car on the track. I am forever seeing cars put onto the track that leave two black lines
behind them as they pull off the line due to having wet tyres. Doing this will make the car a real
handful for the first couple of laps while the tyres dry themselves out on the carpet. Use a towel to
properly dry the tyres and scrub them in the corner of the track if necessary. It has even been known
for drivers to use a hairdryer to properly dry their tyres before a race - Chris Kerswell

Car Setup Using Additive
As previously mentioned, tyre additive can be used to fine tune the handling characteristics of your
car. This can be done in two ways; the amount of additive applied, and the soak time.
Applying additive to a larger proportion of the front tyres will result in more front end bite upon
entering a corner. Doing this will make the car more twitchy and aggressive when entering a corner
and will usually give a feeling of the car having more steering overall. A good base setting is 17mm,
measured from the inside edge (yes, we do measure it in increments of 1mm!). More additive =
more bite! It is not normal to run less than half of the tyre width on front additive; if you find you
have to run less than half of the front tyre width, consider changing the tyre compound or steering
lock settings.
Something that many racers do not consider is the additive soak time. This is basically the time
between applying the additive and wiping it off ready for a race. It is normal to have a slightly longer
soak time for the rears than the fronts. 25 minutes for the rears and 15 minutes for the fronts is a
good starting point.
A shorter soak time usually results in sharper handling and a more responsive car, while a longer
soak time makes the grip last longer and remain consistent through a run.
Racers Tip
The goal with additive soak time is to make the handling as sharp as possible whilst retaining grip for
the duration of an 8 minute race. A car with nice sharp handling is easier to place on corner apexes
and generally gives the driver more feedback. Aim for the shortest possible soak time without making
the car run out of grip towards the end of a run. I have often found myself applying additive to my
tyres just as others in the same race as me are about to start wiping theirs off!
You can manage the tyres a bit during the run to help as well. Taking it a bit easy in the first part of
the race often means you still have good grip levels at the end of the run. This can be particularly
useful in finals if there are cars ahead of you which suffer a loss of grip towards the end. - Nigel Hale
Summary
It is advisable to find a base setting for soak time and amount of additive applied, and to start with
this at all events you attend. After this it’s usually just a case of fine tuning by a few mm or a few
minutes. Don’t be afraid to ask other drivers what they’re doing either; just in case they are doing
something you’re not which gives them a performance advantage.
Hopefully this article has provided a useful insight into tyre additive and how it can be used to
optimize the performance of your car. As with anything technical a true understanding of it[/center]