Tyre Tread

[The End]

Humour me here, why would a slick tyre on a dry warm day not work well on the road?

I'm in need of a new rear soon - currently have a Battlax T30 with just over 16,000 kms on it including 2x trackdays at Hampton Downs. I've been very impressed with this tyre especially with its longevity when compared to the Bridgestone S20 I had on previously which got me around 8000kms before being replaced. It's also been great for commuting in the dry and rain, as well as weekend hoons. I'm just now starting to notice things getting a bit fun in the rain as the tread is getting low.

In looking at new tyres, I've come across the likes of the Michelin Pilot Road 3 & 4, which have a hell of a lot of tread and siping dug in to it. Is there not a point where the more tread you have in a tyre, the less grip you get in DRY conditions? My reason for thinking this is that every gap (tread, siping etc.) in the tyre is one less piece of rubber in contact with the road. Although I suppose I can answer my own question here and assume they have found that margin and have designed the tyre as such.

Not quite sure what I'm asking here, but I'm sure someone smarter will come along with answers.

[AllanB]

You are correct in your thinking - the tread is only there to expel water.

If you have a look at modern sports rubber the 'blocks' of untreaded rubber have been getting larger and larger - this is to reduce the blocks squirming under acceleration/breaking forces.

Modern rubber is full of goodness that helps them stick in the wet so they can reduce tread grooves.

Of course dedicated sports touring rubber like PR3 etc are required to do everything well - on a sunny day they get thrashed like sports rubber, wet expected to contain the bikes power and then asked to last for twice the distance of 'sports' rubber.

It is truely a wonderful time to be purchasing motorcycle rubber.

[Blackbird]

?......Of course dedicated sports touring rubber like PR3 etc are required to do everything well - on a sunny day they get thrashed like sports rubber, wet expected to contain the bikes power and then asked to last for twice the distance of 'sports' rubber.

It is truely a wonderful time to be purchasing motorcycle rubber.

Absolutely! Most of us will never get anywhere near exceeding the performance envelope of tyres from reputable manufacturers and it comes down to personal choice about their characteristics. I ride in all weathers so a pure sport tyre isn't so versatile for me. The D214 sports tyres which were OEM on my GSX-S 1000 were OK in the dry but didn't trust them in the wet. The rear was stuffed at 3700 km too! Replaced them with PR4’s and feel a lot happier in the wet. Recently did a track day on them at Hampton Downs and they stood up surprisingly well. Expect to get somewhere approaching 8000-10000 km from the rear hoop. The bike also turns in more quickly as the PR4 has a sharper profile. It all comes down to how you ride and the conditions you ride in.

[Asher]

Slicks on the road is a bad idea, most riders would never get them hot enough and those that could would probably have a police copper after them.

I have always thought that the more tread a tyre has the faster it warms up.

[Gremlin]

I have always thought that the more tread a tyre has the faster it warms up.

Yes, to a degree, not withstanding ambient and road temperature, tyre compound etc.

Realistically, you have to do something drastic to have a tyre that has bad dry grip, although get it too hot and yes, that's also a negative. I would say there is a reasonable balance there in adding some grooves to increase wet weather grip, and the PR3/4 is usually rated as one of the best road tyres in the wet.

As tyres go from sport touring to supersport tyres you're getting less and less grooves, they take longer and longer to warm up and they can handle less heat cycles (why racers use warmers, to ideally only have one heat cycle a day on the tyre). They also have an increasingly smaller bracket of ideal operating temperatures. It is quite possible to have a sport touring tyre offering better grip than a sport tyre due to the sport touring one having a wider bracket of good performance vs the supersport. However, with both at ideal operating temperature in good conditions, the supersport will definitely have the advantage (through compound, structure and contact patch on the road - less grooves).

Rubber warms up through friction (and sitting in the sun etc but let's ignore). So the more the rubber moves, the warmer it gets. Hard compound tyres take longer, soft compound take shorter amounts of time. The more the rubber can move, the quicker it gets warm ergo, the more grooves a tyre has the more the remaining rubber is able to move around. Accelerating and braking hard will actually get more heat into a tyre than weaving down the road.

As with selecting a motorbike, you select appropriate tyres to your needs. Riding in all weather? Then you want something that can handle dry and wet. A sport touring tyre is what you're after and you'll likely focus on wet weather grip more than dry. If it's a track bike, then you're not going to have PR3/4 (perhaps with exception of Hyosung cup, where I believe they were quite popular). The tyre won't handle the extreme heat you'll likely generate and won't have the ultimate grip of a sport tyre. For racetracks you have wet tyres available specifically for the purpose and they do have a lot of grooves. I was going to say the sport touring tyre will also suffer in length of life, but then supersport tyres don't last that long