Got Any Good Tyre Theories?

When you "Run a tyre in" Do you know what you are doing? Do you think that by roughing up the edges with a file it makes a difference? Do you think Burn Outs do it for you?

Running wets - do you go for higher or lower pressures?

When it's turned wet do you raise or lower the gearing?

Are slicks run at a higher or lower pressure than the usual "intermediates"?

When the temperature drops but it's still dry, do you raise or lower the pressures?

I sent a fax to Dunlop Tyres with some these popular questions, the answers make interesting reading

From: Mr. M. Jackson, Dunlop Motorcycle Tyres, Racing Division.

We only produce D207 GP, race slicks and wets here in Birmingham so all my comments regard these, none of the following comments will refer to tyres never used on the race track)

1. "Do we have to scrub tyres in to remove Mould Release Agents?"

D207GP's of ALL applications use the same moulds. Release agents are only rarely used where we encounter problems with a particular process or compound. D207GP's and slicks are unlikely to have any mould release agents on them. Road and race tyres nearly always use different manufacturing processes due to their different applications.

2. "What is the biggest difference Between Road and Race tyres?"

It's mainly construction (composition), because of this a racing slick is not capable of road tyre mileages - it is generally built for lighter machines without pillions, also a slicks high-speed stability would be much impaired compared to a road tyre. There is a cross-over between the harder end of the slick compound range and D207 GP road tyres. One reason being that it is more efficient for our factory to produce 'common' compounds applicable to standard slicks and D207 GP than to produce a different compound for each and every application. Having said this all slicks and D207's have their own development cycle and no product is never compromised.

3. "How Long does Scrubbing in take?"

'Scrubbing in' depends upon track/road conditions, temperature, rider experience, etc. In my experience two laps is enough for a slick under nearly all circumstances and probably three laps for a D207GP. On the road in the winter a D207GP will need up to 50 miles to scrub-in.

4. "How do wets compare on Pressure?"

Wet tyres are typically run at 0.2-0.3 bar higher than D207 GP's and slicks.

5. "What is the Correct Pressure?"

Correct tyre pressure is just as (more?) important as correct compound selection, a fact which escapes many experienced riders and novices alike. Starting pressure largely relies upon final hot pressures It is always best to find the optimal hot pressure for a machine - say 2.6-2.7 bar for a 600c Supersport 180/55ZR17 D2O7GP rear (on the race track only) and then regulate starting 'cold' pressures to achieve this as ambient and track pressures change through the day. As you point out if ambient temperatures decreased then you would reduce starting pressure slightly to achieve the same hot pressure (assuming the tyre casing was reaching a similar temperature in both conditions), as the increase in casing temperature, hence pressure, must be more in colder conditions. Temperature rise in wets is not significant, it is unlikely these would need to be corrected.

6. "Tyres are only good for 3 runs".

This depends on the severity of the 'runs' and the type of machine. 125cc tyres are generally capable of more 'runs' than a 5OOcc machine. Once any slick or D2O7GP has been raced hard its future performance will invariably be lower although for a novice rider the lower severity of use in a race and the riders lower ability/tyre requirements may mean he can quite happily continue with a tyre much longer than an experienced rider. Top national level riders will only race once on a set of tyres - D2O7GP's or slicks, therefore these tyres are only any good for one 'run'. Heating/using/cooling will affect the chemical/tyre properties to varying degrees but I would say the 3 'run' philosophy is untrue. As I point out a novice may get '6 runs' but an expert racer only 1 'run'.

7. "Wider tyres = More Grip."

Assuming the tyre in question is designed for the rim in question then this is generally true. You should bear in mind however that handling performance generally reduces as the tyre gets wider, so for a twisty track like Cadwell short-circuit more grip does not necessarily equate to faster lap times.

Hope this is of some help to you. Mick Jackson - Chief Designer.

Got Any Good Tyre Theories?

Other questions still out standing.