INSIDE FORT DUNLOP
PH2 storms the ramparts of Dunlop's motorsport tyre facility for the inside story
Sounds like a logistical nightmare? It is, especially as each tyre has to be tracked and recorded to ensure the teams don't cheat.
Where on a single tyre car race series Dunlop actually embeds microchips in the sidewall, motorcycle tyres still use identification stickers. Not that it stops a few of the teams bending the rules. Remember how fast some riders were on the opening few laps of Moto2 during the inaugural season before mid-season they seemed to forget how to ride quick out laps? There is a tyre softening solution that drag racers use to give them immediate grip before the tyre has properly heated up, this is now banned in Moto2...
Stage one involves making the actual rubber compound. Basically that's the black stuff, comprising over 20 different components fed into a machine called a Banbury. Operating like the B&Q paint mixer it automatically measures and adds pre-determined quantities of the compounds into a big mixing pot.
Great British bake off
These are mixed and heated and squeezed out in what looks like big strips of chewing gun. This compound's performance can be altered by the quantities of the ingredients, a bit like making a cake. More silica makes a better wet weather tyre, more carbon black makes it last longer and more oil makes it stickier - which seems a contradiction. Believe it or not, oil is a major component in tyre production with around four litres of oil in a car tyre and 1.5 litres in a bike tyre! And yes, natural rubber from a tree is also added, although so is synthetic rubber.
These beads are combined with the neoprene on one of 10 special machines. Each machine has a metal drum (known as a former) in the shape of a tyre which spins and allows the worker to place first the neoprene, then the beads which are joined together with strips of rubber and finally a nylon ply layer is added for strength. This creates a basic carcass shape, which is then transferred to the £2m MRG (Motorcycle Radial Goodyear) machine. The MRG winds on strips of Kevlar thread coated in rubber onto the carcass in much the same way you would wind string onto a bobbin in a process Dunlop call JLB, or jointless belt.
The Kevlar is twisted together before being coated in rubber and by varying the strength of the twist Dunlop can affect the carcass's performance - a tight twist makes the carcass stronger, a looser one makes it move around more. With this attached to the tyre Dunlop then covers it with a layer of aramid which uses its N-TEC technology developed through racing and essentially holds the carcass together so that it forms a stronger structure allowing lower tyre pressures.
Using a process called JLT (jointless tread), Dunlop winds the rubber compound onto the carcass in the same way that the JLB is added. Starting at one side of the tyre, the rubber is applied in thin continuous strips with the final product looking a bit like it has been made of Playdo.
Should Dunlop wish to vary the compound it simply introduces a new 'rubber' into the strip with no joint. Although some of Dunlop's bike tyres use a flat strip of compound wrapped around a carcass it isn't as accurate as the JLT technology as there is an area at the edge of the tyre with overlap due to the change in the tyre's profile. By using JLT the compound mirrors the tyre's form perfectly, creating a smooth profile.
Rubber attached, what you now have is a 'green tyre' which isn't actually green but hasn't been heated. The final stage of tyre manufacture involves vulcanisation. Nothing to do with Mr Spock, vulcanisation is simply the use of heat and pressure to cure the tyre and make all its compounds work properly, a diaphragm and mould holding in this state for 20 minutes at 10bar and 200 degrees. It is during this process that the tread pattern is forced into the tyre by the mould.
Before being sent from the factory, every tyre is weighed, a balance spot added and then one in 10 is also X-rayed to check the angle of the Kevlar weave in the carcass to ensure it is uniform. Having passed inspection it's off to the store room where the tyre sits alongside up to 50,000 others ready to be picked out and sent to a race meet.
we tried them out not so long ago...