Using Semi-Slicks: Part 1 - Scrubbing In

A simple trick to unlocking lasting performance.


R888 Semi-Slicks being cooked to perfection

A simple trick to unlocking lasting performance.

Running ‘green’, or brand new, competition R-Spec tyres at race speeds, it's easy to overheat or ‘heat spike’ the tyres in their first heat cycle, where temperature and inflation pressures increase more than normal.

A heat spike in a tyre's first outing significantly affects the tyre's performance throughout its life, causing tyre performance to drop off quicker with each heat cycle and use.

This spike and issues following can be easily avoided.

Common wisdom around new R-Spec semi-slick tyres is that they need to be ‘scrubbed’ or ‘bedded’ in. Scrubbing the tyre in is generally deemed as a few soft laps around the circuit the day before competition to around three-quarters of peak temperature, and a day of rest to cure.

Toyo Tires Motorsport

However, it’s nearly impossible to get an even and consistent result from manual scrubbing by lapping the tyres around the circuit. Most people won’t get the chance, with pre-qualifying outings insufficient and subject to rain, and events like hill climbs going directly into competition.

Scrubbing competition tyres is designed to break smaller, weak molecular bounds and reforming them into longer and stronger bonds.

The tyres need to reform, to maximise life and optimise performance. Properly cooling and curing takes about three days before the tyres are race ready.

Toyo Proxes R888 and the soon-to-be-available Proxes R888R will see lifetime performance gains from being correctly scrubbed in.

Masato Kawabata's D1GP GT-R

Gordon Leven and Bill Pearson of Gordon Leven Motorsport Tyres in Emu Plains know competition tyres better than most. At a recent tyre tech night, Bill and Gordon explained the new way of bedding in competition tyres – heat treating.

“Scrubbing tyres in is a binding of what the tread compounds are made of, which you can do on your car at an event by introducing heat,” explains Bill.

“When you do it on your car, you do it with your suspension angles, air pressures, uncertain conditions, cambers, dirt on the circuit, different temperatures and all the other variables of real world conditions.”

A set of Toyo Proxes R888 about to undergo electronic heat treatment

With track time expensive and limited, and conditions impossible to control, getting the most from your tyres through scrubbing in has previously been an inexact science. That’s no longer the case.

“Heat treating gives you a longer window of performance, more consistent performance for a greater period of time and less drop off grip wise.”

A set of Toyo Proxes R888 about to undergo electronic heat treatment

Gordon Leven Motorsport Tyres offers an electronic scrubbing service where tyres are placed in a highly-controlled oven and turned at 65- to 85-degrees celsius so heat penetrates the entire tyre.

“We do it with a very constant heat that covers the whole tyre. The heat goes through the tyre to the case without wall flexing, debris on the circuit or the other pressures of actual driving. You’re binding the compound internally,” Bill says.

“When you have a green competition tyre you get a performance and heat spike. When you don’t bed them in properly, that spike then falls away, fast.

“The better you prepare the tyres the longer that spike lasts before it falls away again. The more care you take the more you get out of them, always.”

A set of Toyo Proxes R888 about to undergo electronic heat treatment

Heat treating means you will see a wider window of life and higher performance from the tyre, more consistent lap times and maximum fun on the circuit.

Heat treating even works on street tyres.

A set of Toyo Proxes R888 about to undergo electronic heat treatment

“We are even heat treating road tyres for discerning drivers,” explains Bill. “Daily driving might mean a tyre never goes over 50-60 degrees so it never really beds in and the molecules never properly join. Heat treating means a longer and more consistent performance life for street tyres too.”

Gordon Leven Motorsport Tyres are a Toyo motorsport tyre specialist, contact them on (02) 4735 4500 or head to 133 Russell St, Emu Plains NSW 2750.