BertoBerg 

Hello All-

I was just cleaning my Masi and noticed that it looks like I installed my Grand Bois Cypres Cerfs backwards. With my previous Grand Bois tires whenever I installed the tires with the tread arrows pointing forward the tire name label was always on the drive side of the bike. I guess when I installed these Cerfs I just assumed this would be the case. On the Cerfs the tread arrows are pointing backwards when the tire name label is on the drive side of the bike.

Is it safe to say that I put my tires on backwards?

HTupolev

Yes, but if the tire doesn't have a label on the other side, the other orientation is also backwards.

BertoBerg 

The other side doesn't have a label. Pretty goofy.

P!N20

I say no. That tread pattern isn't doing anything to dispel water and if you're leaning that far over on your bike you've probably got bigger issues.

Jobst thought tread on bicycle tyres was useless: https://www.sheldonbrown.com/brandt/slicks.html

Jan thinks a bit of tread is preferred, but even he says the direction isn't important: https://www.renehersecycles.com/myth...r-on-the-road/

downtube42

Aesthetics.

ThermionicScott 

The way I reconcile those two viewpoints, is that Jobst didn't seem to mind the light file-tread patterns on the tubulars he enjoyed for years:

"I rode Clement Campionato del Mundo tubulars and some Paris Roubaix until Specialized offered the Touring II so called 700-28c tire, the first reasonably available and durable clincher."

"When Avocet decided to enter the tire market I convinced them to make a smooth tread tire, a slick, because that is essentially what we rode in the days of tubulars, the tread of those tires being about 1/2mm deep when new." (https://yarchive.net/bike/tire_color.html)

His real objection seemed to be larger knobs and grooves in tire tread, if I parse his writings correctly.

canklecat

Every time I think shallow, superficial tread on skinny road bike tires serves no purpose, I ride in rain and decide maybe it does help.

I've ridden in all conditions, including downpours and patches of ice, on Continental Ultra Sport II -- slicks, because the patterns in the sidewalls never contact the ground in normal riding -- and Conti GP Classics, their retro-style skinwalls with diagonal slashes in the raised center tread, and shallow herringbone tread on the shoulders. The GP Classics definitely grip better in the wet, which I got a refresher in Monday evening during a downpour. The Ultra Sport II are excellent values and not bad at all in rain, but I did need to mind my hard braking to avoid skidding, and my cornering. The GP Classics grip better in both conditions.

But... they also use different compounds: Pure Grip on the Ultra Sport, Black Chili on the GP Classics.

And I've ridden Conti's Sport Contact II, with shallow file tread; and SpeedRides, with medium depth diamond tread, the type that's very popular with gravel tires in general and some cyclocross tires for dry conditions. Both grip significantly better in the wet than the Ultra Sport, or any chevron tread tires with more pronounced, deeper tread.

I'm leaning toward the theory/assertion by some tire manufacturers that even superficial tread creates just enough friction and heat to be effective in the wet. That might make some tires slightly less efficient on perfect dry pavement -- that increasingly rare beast once known as asphalt or tarmac. I rarely see that anymore, as the new normal pavement in Texas is coarse chipseal, like railroad ballast glued down with epoxy.

These tires are all marked with direction arrows (which, of course, are difficult to see), but I've mounted them "backward" a few times and didn't notice any difference in performance. But I fixed the orientation as soon as I noticed, so I haven't spent much time riding the tires mounted incorrectly, including in the wet. I doubt it matters at all with the fine file and diamond file tread patterns, which show no indications of being directional despite the arrows on the sidewalls.

BertoBerg 

Thanks for the input everyone.

The Golden Boy 

My guess is it does matter.

People are mentioning rain- and water siping channels are the tire technology that keeps you from hydroplaning. The channels allow water to be diverted out of the way of the rubber- so the rubber can meet the road.

Now- how much of a difference does it make for a bicycle tire, and the location of the sipes- in that location, are they more decorative than functional? Is throwing the water "out and forward" different/better than "out and back." I don't know.

Personally- I'd point the arrows forward- if for any other reason, it would drive me bonkers otherwise.

BertoBerg 

Yeah, its kind of driving me nuts...

The Golden Boy 

HTupolev

The high pressures and low speeds of bicycle tires make hydroplaning basically impossible regardless of tread pattern.

gearbasher

I've ridden Vittoria Rubino Pros for years. They used to have an arrow on them. Now they don't. Same tread pattern. Does it matter? I still put them on in the same direction.

davester

My thought exactly. If the tread has any function at all it is to increase the roughness and therefore frictional resistance to sliding, not to channel water away.

AlmostTrick

I have 28mm Grand Bois tires on a fixed gear bike. The rear wheel gets flipped around depending on which gear I want to ride. I've never noticed a difference (and have ridden it in the rain) and don't believe anyone could. Then again, the front tire was always spinning the correct direction so maybe that saved me from certain death.

downtube42

Interesting you cite the specific tire - Sport Contact II - that slid out from under me on a wet corner. Obviously it could have been a spot of oil or whatever, but I do hold a serious if irrational grudge against that tire. I had a shredded elbow, slight concussion, and some bike damage. I finished the ride - a 600k brevet - but I was a confused and a bloody mess.

My normal tires, Primo Comets, were pure slicks and even had a reputation for poor wet performance. I returned to those, and never had a problem since.

I'm on the page of it doesn't matter, but I also don't have any real data to back up that opinion.