What difference do different tyres make? They seem to be sold as separate fronts and rears. And those half-bald ones look scary. Sponsored riders seem to ride whatever theyre told to, and a £12 tyre looks pretty much the same as a £35 one in the shop. How should I decide which tyre is best for me? Im currently using a pair of IRC Mythos, which seem fine but are starting to look a bit ragged. Sorry if this is a stupid question.

Beth Hebdige, Hebden Bridge

Its not a stupid question at all. Front tyres look different to rear tyres simply because they do different jobs: in a nutshell, the back tyre has to have traction to push the bike forward, while the front tyre needs to be able to force the bike around corners. The knobbles on the back generally run across the tyre and dig into the ground as you pedal. But the tread on a front tyre runs along the line of the wheel, only creating resistance when you apply a turning force.

Next thing you need to consider is that different riding conditions suit different tread patterns. Tall, thin knobbles dig into soft mud and grip well. But use them on hard ground and the tyre will squirm around. Making the knobbles out of a denser material helps, but then the tyre can get heavy.

I used to use a tyre that got around this by combining dense knobbles and a lightweight carcass. Unfortunately, the knobbles didnt like the carcass and dropped off in droves.

In dry, hard-packed or dusty conditions, big, chunky knobbles packed close together give excellent grip. The trouble is that theyll pick up mud as soon as look at it. A chunky tyre like this will soon become clogged, heavy and ultimately useless in muddy conditions.

Rubber quality makes more of a difference than most people think, which is why a £35 tyre will behave differently to a £10 copy with an identical tread pattern. The general rules for choosing tyres are to pick a reputable make, buy a matching pair and replace them frequently. Clean, sharp profiles always grip better than worn ones, so replace your tyres as soon as they start to get worn.