Tread on road tyres?

[Dave W]

Following on from another thread.

Is it there for a purpose, does a treaded tyre actually do anything on the road that a completely slick tyre doesn't?

[AlaninWales]

Road tyres are usually slick(ish) because this maximises rubber in contact with the ground, however for improved wet performance they will have a small light tread cut into the single slick 'block' = siping. http://en.wikipedia.org/wiki/Siping_%28rubber%29

[thirdcrank]

The minumum tread depth regs for motor vehicles were only introduced in the late 1960's when the typically higher speeds og motorway traffic led to the recognition of aquaplaning as a problem.

I'll say treads are pointless on road bike tyres, a point made somewhere by Sheldon Brown, but he calls them tires.

[kylecycler]

This should help - technical info from Schwalbe - their answer is on page 14:
http://www.schwalbe.co.uk/_webedit/uplo ... 20Info.pdf
"On a normal, smooth road, even in wet conditions, a slick tire actually provides better grip than a tire with a tread because the contact area is larger." They also say "A slightly serrated surface on the tire tread can have a positive effect on tire grip, as it creates micro interlocking with rough asphalt," which presumably is 'siping', referenced in AlaninWales' post. Schwalbe also explains that a bike tyre would only aquaplane (theoretically) above 200 km/h.

What always concerns me though is, if there's no tread, like on a slick tyre, how do I know when to replace the tyre?

[andrew_s]

Tread can be handy if there's muck on the road, such as cow poo or leaf mulch.
You may also get a bit of warning about impeding loss of grip, although that loss will come sooner.

[andrew_s]

What always concerns me though is, if there's no tread, like on a slick tyre, how do I know when to replace the tyre?

That is a problem.
Sometimes there's a layer of rubber of a different colour that acts as a warning, otherwise you can either take the tyre off so you can check how thick the tread is or just wait for it to go fluffy.

[thirdcrank]

... which presumably is 'siping' ...

Afaik, siping refers to the action of features in motor vehicle tyres - sipes - which clear water away from the tread to prevent aqulplaning, which occurs when the build up of water under a tyre at speed causes it to lose contact with the road. Look at a smooth, wet road after a car has been driven over it an there will briefly be dry stripes where the tyres have cleared the water.

[AlaninWales]

I've run slicks and semi-slicks most of the time I've ridden on roads (mind you, that has usually been with a 'hybridised' (bastardised for the purists?) mountain bike frame and 26" wheels, often a hub gear too); I've never found them a problem on dry or wet roads, or even snow (Richmond Park) or mud* and wet stone (Wey Navigation). Narrow-section tyres OTOH have spat me off on damp (oily) urban roads many a time before I settled for the fat ones.


*ETA: They may spray a bit, but keep pedaling and you make progress - as long as you don't need to climb much

[foxyrider]

What always concerns me though is, if there's no tread, like on a slick tyre, how do I know when to replace the tyre?

You'll know! Typically the tire will develope a flat top to the riding surface. Some tyres now have wear indicators built in.

[thirdcrank]

Unlike a car, it doesn't matter too much if you don't realise a bike tyre is getting badly worn. The worst that's going to happen is that you'll get a flat and then discover that the tyre's too bad to continue. (Speaking from hard experience, don't let it happen far from a bike shop during business hours.)

[meic]

I find that all tyres have a built in wear indicator. This shows up as you wear through the rubber, it is sometimes a coloured plastic layer, sometimes a material fabric that pokes through.
After this shows you can put in an order for a new tyre and fit it when convenient.

[Mick F]

Mt tyres have - or should I say HAD - a fine tread. They wear away within the first few hundred miles, so basically I ride on slicks.

[iandriver]

If you view tread as channels for water to disperse along having been forced out of the way by the contact point on a wide tyre, then there is an equivalent on narrow slicks. The channels are the fresh air each side of the tyre.

[mercalia]

I think the tread on bike tyres more to do with giving them a decent life at not too high a weight & rigidity? If eg a standard Marathon had no tread but the same thickness, it would be far heavier & less compliant - a bit like riding a solid tyre?

[michael42]

does a treaded tyre actually do anything on the road that a completely slick tyre doesn't?

In theory it'll reduce grip.

I'm sure tyre manufacturers sell treaded tyres because that's what the market wants.
i.e the naive market believes that tread is there for wet roads and that 'tread' is what makes tyres grip. Which on cars it is
there for a reason, but although there's less grip on a wet road on a bike they don't aquaplane, unless you're incredibly fast, so tread won't help.

Logically therefore you'd expect nigh on every bike tyre to be slick. Yet they aren't, so the assumption must be
that they are selling what people think they need rather than what works best.

I often see treaded tyres described as for "British weather" on new bikes.

The exception is if you're riding on a surface that's soft. i.e if you come across mud then tread gives you grip (but usually then you need MTB or cyclocross tyres)