Right. You need to hit 93-104 MPH to get an 80-100 PSI road tire to hydroplane and even at 40 PSI it takes 66 MPH.

I agree, this thread doesn't matter.

j/k - you might be on to something here. The compound I had never given much thought, but the worst wet-weather skidding I've done was when riding those bontrager hardcase tires. I never did like the type of rubber on those tires....I also have had one pretty good skid on a cont. gator skin.

Meh - it's worth a thought.

I love the Bontrager Hardcase specifically because they last a long time and are practically bulletproof. But...as mentioned earlier, this means the compound is harder. Hard= poorer wet weather traction. I'll sacrifice some traction for better flat resistance though.

I ride 25C Bontrager Race Hardcase Lites on my summer bike and 28C Schwalbe Marathon Supremes on my winter bike. My personal experience is that the Supremes are much better in the wet, and they throw a lot more spray than the Bontragers. They also ride a lot smoother as well.

Yes. The surface interaction which causes friction is ridges and valleys not just at a microscopic but at a molecular level. Shapes and positions of molecules and forces which act on molecules. Even more counter-intuitive is the realization that the size of the contact patch does not matter.

For tires, in softer rubber compounds generally have better traction but, being softer, wear out more quickly. Water does affect friction as does other "stuff in the middle" - hydrocarbon molecules - but again surprisingly this stuff in between surfaces enhance (or allow) friction . e,g, https://www.sciencedaily.com/releases...0603163257.htm so it's no stretch that some compounds would be better on wet roads than other compounds that otherwise give better traction.

Does tread make that much difference when commuting in the wet? No

It's the compound, not the tread that interfaces with the pavement. Because of the rounded shape of a bicycle tire, they simply aren't able to hydroplane at speeds that are attainable on a bicycle, and, if you are going that fast, your tires are going to be far down the list of things to be concerned about.

Sheldon Brown (RIP) was one of the most respected voices regarding all things bicycle. Here is what he had to say about tread features on bicycle tires:

Tread for on-road use
Bicycle tires for on-road use have no need of any sort of tread features; in fact, the best road tires are perfectly smooth, with no tread at all!
Unfortunately, most people assume that a smooth tire will be slippery, so this type of tire is difficult to sell to unsophisticated cyclists. Most tire makers cater to this by putting a very fine pattern on their tires, mainly for cosmetic and marketing reasons. If you examine a section of asphalt or concrete, you'll see that the texture of the road itself is much "knobbier" than the tread features of a good-quality road tire. Since the tire is flexible, even a slick tire deforms as it comes into contact with the pavement, acquiring the shape of the pavement texture, only while in contact with the road.
People ask, "But don't slick tires get slippery on wet roads, or worse yet, wet metal features such as expansion joints, paint stripes, or railroad tracks?" The answer is, yes, they do. So do tires with tread. All tires are slippery in these conditions. Tread features make no improvement in this.

If you want to read the entire article on bicycle tires, you'll find that here: https://www.sheldonbrown.com/tires.html

The total irony here is, our wet weather road racing tire has a very subtle tread pattern, and my initial reaction when we got them was (WTH??? or some other consonant). We even state somewhere in our literature that "slicks" grip better than tread feature tires. So, at Interbike I asked the person in charge of such things (they come over every year from Germany to see how we do it here) point blank, "Wha?". The response mirrored almost to a word what Sheldon Brown said, that the tire wouldn't sell very well without the tread pattern, and that it would technically be a better tire if it didn't have them. Now, the tread pattern is very subtle and the difference is too small to really make a difference, but even out tire engineers, succumb to market pressures. We are in the business of selling tires after all.

There ya go. From someone who really knows.

Thanks for an even better discussion than I'd hoped for, guys. Learned some here.

I've always compromised wear for softer compound, given the nature of my riding environment. This time, I'm likely going to go for a pair of Supremes from Mr. Kojack's employer - a big-money move from my usual Kendas - because, well, in addition to being highly functional, they're pretty.

So, our literature qualifies this statement a bit, if the roads where your ride are excessively rough, then a tire with tread features may have some benefits. Hard to know where the tipping point is but where I ride the roads are fairly well maintained and for as long as I can remember I've always used slick or mostly slick tires.

From our website: https://www.schwalbetires.com/tech_info/tire_tread
Why ride a slick tire?

Even in wet conditions, on a normal, smooth road, a slick tire actually provides better grip than a tire with a tread, because the contact area is larger.
The situation is much different on a rough road and even worse on a dirt trail as in these cases the degree of control provided by a slick tire is extremely limited. A slightly serrated surface on the tire tread can have a positive effect on tire grip, as it creates micro interlocking with rough asphalt.

I certainly feel less stable in the wet on more aggressive tread (leaving less rubber on the road).

Completely unrelated question...what is a "LCF"?

Well, I've used the Kwest and I can say that the compound makes a huge difference. Tread matters in mud, not on streets in rain.

Ditch the Kwest and get Schwalbe Marathon Supreme tires. I get three times the stopping traction in the rain on those.

Living Car Free!

check if the tires are nylons. nylon tires get slippery in wet weather. the majority of solid rubber tires will still give decent traction on wet pavement. i have been using slicks, Schwalbe Kokaks in rain and a few times caught is hail storms, and the tires have kept traction. when i know i am riding in wet weather, i will drop my tire pressure by around 10 to 15 pounds to get a bit more patch on the road. i reserve my max psi for dry rides.

In my NW commuting experience. It is a yes and no answer. If you are on purely wet pavement, slicks are best, something with a supple rubber (high tpi?). If the road tends to have any dirt, mud, unknown slime, or what ever, having just a little bit can make a noticeable difference.