Leyland P76 Owners 2004

DUNLOP TARGA TYRE TIPS

by Geoff

Some tyre tips from Targa NZ last year.
Good tyres, suitable for the performance capabilities of the vehicle, are an essential part of your car preparation.
Many of you already have plenty of prior experience to know exactly what you need while others will be entering this event for the first time and may even be competing in their first motorsport event.

SELECTION

There can be several tyre options to go through before coming up with a final recommendation but if your plans also include new wheels you should establish the optimum tyre fitment BEFORE wheel selection.
Generally, if your car is reasonably standard, or of earlier vintage, a good modern high performance road tyre such as the Dunlop FM901, or even a LeMans A5 or Monza 200, can be perfectly satisfactory.
For the more modified or later high performance vehicles then you should be looking more towards a 'competition' based tyre such as the Dunlop Formula - R
Remember that this event covers a lot of the country over several days and wet weather is almost inevitable at some stage. While the regulations require tyres to meet WOF standards at all times good wet grip is very important and the more tread depth you have the better the tyre will cope with wet roads. Start the event with tyres as new tyres possible even when you don't expect to wear them out.
Remember, widest and softest is not always the best. You need good tyres but it can also be possible to have too much grip which can make the car quite hard to drive and prone to 'bogging' down.
Our Dunlop representatives are available to discuss your tyre selection with you at any time.

FITTING

Check that the wheel width and diameter is correct for the tyre size being fitted.
Fit new Tubeless valves
Check if tyres are directional or asymmetric and ensure they are fitted the correct way.
ALL TYRE FITTING SHOULD ONLY BE CARRIED OUT BY QUALIFIED PERSONS.

TYRE CARE

All new tyres benefit from a 'running in' process. This is best achieved by running under normal road conditions, but avoiding harsh starts, hard cornering and braking, for around 100km.
If tyres are to be 'scrubbed in' on a racetrack the following procedure should be followed:
Much as you would 'warm up' an engine bring the tyres up to an even operating temperature over 2 or 3 laps. Speed can then be increased to around 75%, 80% and 90% progressively over the next 3 laps followed by a lap at full race speed.
This should be followed by a cool down lap and then let the tyres cool naturally to ambient temperature. The cycle is then complete.
If tyres are to be stored for any length of time they should be kept in a dry, cool, dark environment away from direct sunlight, electric motors and welding equipment.
Any contamination from fuel or oil must be cleaned off immediately.
The best 'dressing' to use is silicon and water but avoid over applying or contaminating floors or interior surfaces, as silicon residue is very slippery.

TYRE PRESSURES

There are no firm rules for 'ideal' pressure as driver, vehicle and road conditions all have an influence.
If you are using road tyres likely COLD-starting pressures will need to be between about 35 psi and 40 psi. Heavier vehicles may need even a little more.
For 'competition' based tyres such as the Dunlop Formula - R the increased casing stiffness allows lower pressures to be used. As a guide this type of tyre can start with COLD pressures from around 24 psi for light vehicles and up to 28 - 32 psi for heavier vehicles.
The vehicles original (handbook) pressures should be used as a guide as to whether the particular vehicle needs much difference between front and rear tyre pressures. This differential should be maintained even though the competition pressures may be somewhat higher.
Fine-tuning can then be made to influence the balance of the vehicles handling characteristics. Generally increasing pressures in the front relative to the rear will reduce understeer and vice versa (more to the rear) to reduce oversteer.
Once preferred inflation pressures have been established to suit the car and driver little, If any, adjustment is necessary or desirable for wet conditions.
Last updated
Dec, 2005
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