I'd search on this if I could search, but alas that function isn't working at the moment.

I changed a flat today and after re-mounting the tire noticed that there was an arrow indicating tire rotation direction on it. Naturally, I mounted the tire backwards, based on this! Sigh...but it did make me wonder....does it matter?

Thanks,

Sheldon

I did that once...then took it off and remounted it. My lbs guy says it doesn't matter.

For it to matter to you in any way besides esthetically you would have already been aware of these directional arrows .

Now you're gonna have to pedal backwards.

For a road bike it doesn't matter, but mtb tires are made with a tread designed to rotate in a specific direction.

My quess is that it would matter on a mountain bike, but not be critical... It would impact traction and handling, but not enough to make the ride unmanageable, just enough that you aren't riding an optimal setup. If I had a mountain bike tire pointing wrong I would change it.

On a road bike, I have a pair of continentals with arrows, but there isn't enough tread that I would expect it to matter. If there is a difference, I think it would be even less critical than on a mountain bike. If I had the arrow on a road bike pointing the wrong way, I would probably ignore it, until the next time I had the tire partly off for a tube repair, even then I might forget about it.

Uni-directional treads are designed for maximum traction in one direction only. A road tire with few tread grooves on dry pavement wouldn't matter much, but in the wet the difference could be significant as the grooves are there to shed the water out from under the tire. With the grooves backwards you are actually trapping the water under the tire. That said, I would install them correctly just because it would bug me.

FWIW, there is also a preferred rotation for the wheels. The inbound pulling spokes should be on the driveside. It really doesn't matter on the front wheel except that it just looks better if it matches the rear wheel.

Al

I really don't mean to sound like a smart a$$ here, but doesn't the location of the sproket/cassette etc. really make sure that the rear wheel is always mounted correctly? Are you talking about paying attention to this when building the wheel?

This is false, your bike never travels fast enough for hydroplaning to become an issue. The "treads" on a road tire are decorative issue only. A slick tire will provide the most grip in both wet and dry conditions on paved surfaces. Automotive dogma does not apply here.

It's a wonder why tire manufacturers feel the need to put any treads on tires at all. I guess its for the general public who think the exact thing as above ^. I would love to see all slick road tires become more prevalent then decoration tires.

https://www.sheldonbrown.com/tires.html#hydroplaning
https://yarchive.net/bike/tire_directional_tread.html

I always mount my tires with the label on the right, centered on the valve, as tradition dictates. On one set of Continentals I have, that results in the tread patterns going in opposite directions. Things like that bother me, even though I know it makes absolutely no difference.

I noticed after a couple years of commuting with my mtb, that I had my front tire mounted in the wrong direction according the arrow. I switched it and immediately noticed my ride was much quieter and smoother. At least on MTB it is noticable.

I had a similar experience when I went to the trouble of mounting a pair of cheapie Michelin Liberty tubulars with the label on the right. I then noticed that the end of the base tape was facing the direction of rotation, so it could conceivably peel back at the corners. It would have been better that the "cheapie" labels didn't show on the "good" side of the bike.

Yeah, on the rear it would depend entirely on how the wheel is laced. Occasionally I'll see one that was laced incorrectly. But on the front sometimes they are mounted backwards, still not a big deal.

Al

+1

Perfectly slick tires are the best for on-road applications. (1) Bikes can't hydroplane, and (2) a perfectly slick tire maximizes the area of tire rubber in contact with the ground, and thereby maximizes traction. As Jobst Brandt explains it, tread can improve traction IF AND ONLY IF the ground is actually soft enough that the tires can actually make a dent in it.

Sheldon Brown also agrees that tread directionality is irrelevant for the road: https://sheldonbrown.com/tires.html#direction

Based on what I've read in this thread and what I've been able to dig up on my own in a short time, I stand corrected. Still skeptical, but corrected, for now.

I just mounted a pair of Continental Gatorskins with the labels on the same side and the "tread pattern" goes in opposite directions. It's really just a decorative design not a real tread. I'm doing my best to ignore it.

In case you're wondering if you can fit 28mm Gatorskins on your bike, don't worry about it. They are really only 25mm's wide. I think you have to buy 32's to actually get 28's. The only tires I have that measure as wide as they're supposed to be is a pair of Tufo 28mm tubulars.

My understanding of rotation directional arrows is to observe them on the rear and reverse them for the front. If the tread pattern is functional this sets up the rear for best traction on power transmission and the front for braking. This sounds reasonable enough.

If the road is harder than the tire, treads do nothing to improve traction. Treads can only improve traction on a soft surface where they can dig in. Mountain bikes need tread. Road bikes don't.

That's an unpredictable and variable "if."
Wet or dry aren't the only surface traction variables. Road or commuter bikes may unexpectedly encounter fine crushed gravel, blown sand, snow, slush, dirt, construction areas, etc.
Country roads, bike paths near beaches and riverbanks, converted rails-to-trails, some stretches along Rock Creek Parkway (DC), or even less-traveled roads popular for century or other organized rides, from time to time present traction challenges.

In some areas of the continent one could probably safely assume excellent road surface traction for most days, but many folks reside in areas where it can change daily, or by mile, or even hourly (by weather).

All I know is that the colored labeled side that is larger goes on the same side as the der. Always worked for me. Never had directional problems with this method.

FWIW, I put a pair of 27" Tioga Bloodhounds (narrow knoby lites) on my partner's UAB and the sidewalls have "<--- Rear/Front---> rotation arrows moulded in to them... the tread pattern is asymetrical. This would seem to support the power delivery traction/front braking traction theory.

In other news, water is wet.

That ensures the rear wheel is mounted right but that has no bearing on the tire. Tires can be flipped around every time you put them on.

Oops! Shoulda checked the last comment date....