Shape and size ?? Makes sense to me that a 10mm wider tyre on a half inch wider rim would give an increased contact patch ? - happy to be proved wrong
Oh, I'm not out to prove people wrong Rob, just dispelling a couple of common myths.
1/ Wider tyres does not necessarily equal more rubber on the road, and
2/ more rubber on the road does not necessarily equal more grip.
The key is the relationship between force, area and pressure, which is a really easy one *blows dust of GCSE physics book*
Pressure = Force / Area
Therefore Force = Pressure X Area
and Area = Force / Pressure.
A nice linear relationship... that means that's all other things being equal, if you make the tyre wider you make the contact patch wider, but it will become narrower front to rear to compensate.
You can lower overall tyre pressure to get more rubber on the floor, but this reduces the per unit pressure on the floor, and with less mass pushing each sq cm onto the Tarmac, you may find the overall level of grip is lower.
Seems counter intuitive I know, and with only a 10mm change it's largely irrelevant. But I thought it worthwhile pointing it out.
