Hi , we recently have been using the new BRM E25M tyre at FPR.
It has produced excellent traction.
However there are a few requirements to take the benefits of the maximum traction they offer.
1. A smooth surface track is best for most BRM tyres. They work on rough surfaces but not to maximum traction.
2. A clean surface free of any dust or ‘Marbles” left from other types of tyre being used in previous races.
This is due to the tyres ’Sticky’ surface it produces when working at its best traction . It will pick up dust and particles from produced by tyre wear.
This is a standard happening with any tyre that has a adherent surface.
We used to get the same occurrence in the days of Indy Grip silicon tyres .
3. So particle pick up could be experienced if the track has particles on the skirts of the track and the car takes an excursion out into the “Marbles”
It may take a few laps to dislodge the particles .
So far this has not seemed to inhibit the performance - but it could.
This is an occurrence similar to full size car racing. But in full size racing it seems to be more of a
problem when cars get off line - as pointed out many times by race commentators .
4 if using the E25M I suggest the track surface be vacuumed prior to the practice & race program starting . We do this at FPR and don’t seem to have too many particle pick up problems .
5. Using a class like Scale Auto with MJK tyres prior to running cars with BRM ( or other rubber tyres) can cause a temporary loss of traction. This is because of the Urethane tyres
removing the BRM conditioning on the track surface.
Also the Urethane tyres leave dust traces on the surface.
After a heat or two with just BRM or the rubber tyres the surface will be reconditioned
and maximum traction will return for the BRM & rubber tyres .
This problem has been discovered at other raceways using a mix of rubber & urethane tyres consecutively .
So the suggestion is to run the Urethane tyre classes after the BRM or rubber tyre classes are concluded.
The situation does vary with some classes unaffected by running urethanes prior to rubber tyres
Alternatively we do run 4 track cars fitted with BRM tyres for a few minutes before
the following class with BRM ( or other rubber tyres ) is run.
The Urethanes seem to enjoy more traction when running on a track after BRM tyres being used.
6. The new BRM tyre also needs a run in period of about 200 laps on average. Some cars bring the tyre to
maximum traction very quickly but others can take a fair bit of running to get maximum traction.
The traction seems best when both tyres have a sheen on the surface and the surface is “tacky’ to touch.
7. Heat can affect tyres - so keep them out of any direct sunlight or away from heating devices .
8. All tyres run best after being trued on a tyre lathe. I have found that most tyres run best with a rounded edge
on inner & outer . Rounded with sandpaper on a block so that any edge & sidewall
Run out can be reduced by very light application of the sanding block ,
You can usually fell vibrations in the sanding block if there is edge runout ( and on the tyre track surface )
Before each race heat & while running the BRM tyre s in we use a track sanding bench at each driver’s
console . this is fitted with 300 to 600 grit water resistant sandpaper .
The surface of the sand paper is kept clean & just moist with water from a spray bottle.
Tyres only need to be spun on this for 5 secs or so and this will remove any adhered dust
and return the tyre to full traction
9. With following the above recommendations most cars will exhibit faster lap times with the new BRM tyre .
Hope you enjoy the new compound in the BRM tyres .