Modern Vespa

My new GTS300 has City Grip tyres, and the tread grooves form arrows pointing one direction around.

When I look at the tyres from the front of the scooter, the front wheel arrows point up while the rear wheel arrows point downwards. I presume the tread is designed to squirt water out from under the tyre, so to me the rear tyre looks correct, with the point of the arrow coming into contact with the road first, and water getting squirted outwards as the rest of the arrow groove comes in contact.

The front tyre looks the wrong way around, but I can only find one thing on the side of the tyre that looks like a pointer and it indicates that the tyre is correct. Why would the tread arrows of front and rear tyres point in opposite directions?

I have googled scooter tyres, but cannot find any clues there.

Mike

The rear tyre experiences highest forces when accelerating, the front when decelerating.

Yes, that makes sense, but what has it to do with the direction of the tread and squishing water out of the way?

I found about a dozen photos of scooters with City Grip tires on the front and all had the tread pattern pointing "up", or opposite the direction of rotation. It looks like yours are mounted correctly. Other pictures of scooters or motorcycles as well show similar tread patterns which appear to "point up", like the City Grips -- except for some that have a centerline groove. It does seem counter-intuitive but I'm sure tire designers know more about tires that me.

Keep the rubber side down!

P.S. Just a wild-assed guess that the front tire tread is designed to pull water away from the edge of the tire, for better traction in cornering?

Yeah, I don't understand it either. My Guzzi has had Metzler and Michelin tyres with the same "odd" pattern that you speak of, with very clear arrows on the sidewalls indicating tyre direction. So there must be a particular reason for this. Anyone worked in the tyre industry that can explain?

They have arrows on the side too telling you which direction is right.

Correct!

arrows point with the direction of travel

so the arrow should be pointing down when looking at the left side at the 9 o'clock position .

We're talking about two different "arrows" here: the markers stamped in the sidewalls to indicate the correct tire rotation, and the "arrows" or chevrons formed by the tire tread pattern. The tread patterns seem to be "backward", but I think that's the way they're supposed to be. Anybody know the reason?

Tyre tread opposite to the direction of travel (on the front wheel) is common on motorcycles. The theory is that the reverse direction tread improves braking.

1. This is correct.
2. The tire manufacturer has engineers that work this out so you don't have to.

Don't worry.

All tire tread designs are about traction, water and or snow , sand or mud with noise thrown into the mix. Wear too.
When i worked for Goodyear we were shown their movie of tires testing on their track which had glass panels to study water dispersion to improve tread design.
Certain aspects of tire design are rather obviously intended to sell tires, not make them better performers-this is especially true for the PU truck tires and their "macho" sidewall stuff, that aside from their naming.
Some car tires simply say inside or outside to make the direction "more stupid proof".
The TWI on some tires seem well placed for safe use while others the tire is very unsafe as little water groove is left at that point.

+1

No worries here but curious about tire tread. Its an interesting discussion.

Best
Miguel

Does this mean the tires are labeled left and right? I've never seen that on any tire but I've never had tires with asymmetric treads either.

Best
Miguel

Perfect example is the Corvette and some Camaro models have directional tires.

Just 'Outside' on the Nokian tyres on our camper van. All the tyres are identical.

Just had a set of Made in the USA Goodyear Eagle Sport 245-60R18's mtd on my X3-that was my reference. Also required was a new set of TPMS sensors to get the low air message off the gauges.
Those a whole nother subject! The ones I went with are set for my cars VIN and brand named HUF/BERU, made in Germany. There's a bunch that will work. The batteries are said to last 5-12 years when I read for info., so it matters to buy fresh stock!
Given that some PTW's have TPMS it matters all around. Mine re-set via the vehicles system whereas some do not. I read of those who paid some serious money to have a dealer do teh puter hook up route, not counting they bought car brand name parts too. Talking over a $1,000 bucks one guy paid-PLUS! the tire aspect.
Lots of ignorance still showing in tire shops toward the sensors. You would think they had it figured out by now, even if I didn't?
I'm now running non-run-flat tires! Have a spare, jack and a lug wrench now to make sense out of a stupid so-called solution BMW foisted off on the masses.
There are several schemes for marking tires.

OK, so no explanations here. I have just Googled the question, and found a lot of "science" that explains nothing. Guess its another of those unanswerable questions like why does the universe exist.

To squish water away from the centre of the tyre, one needs the point of the tread arrow to come in contact with the road first. So the front tyre is the wrong way around. Perhaps some expert had an off day and put a tyre on the wrong way, and everyone followed him blindly ever since. Alternatively, perhaps the pattern has nothing to do with moving water, and other forces are at play here, but I cannot find any explanation. Acceleration (rear tyre) and braking (front tyre) forces are in opposite directions, so maybe this is related somehow.

Anyway, I can live with my tyres having opposite tread patterns, I won't lose any sleep. Thanks for the replies.

Mike

I can tell you from direct work experience that tire companies don't share information like what you hoped to find. Michelin is said to be one of the most shrouded tire companies process wise. Quite unlike Goodyear where my apprenticeship allowed us (12 each years class group) to spend 8,000 hours in all aspects of the largest tire plant in the world, including engineering and everything else except paper shuffling, Michelin kept most of their people sequestered per what we heard from the rubber industry grapevine. Seems they even had visual barriers between processes.
Most of what we see from tire companies is all marketing gibberish, not science. The tread is only one aspect, others are the tires build via coated plies and beads plus compounding of various rubbers that go into the many parts. Lots of goodies in those things and yet they are handmade-on a machine of course. Sort of like a shoe.

It's always seemed 'right' to me. You need the front tyre to have its best water-shedding capabilities when cornering at speed. The bike will be leaned over - the water needs to be squished from the outer edge towards the middle - the opposite to what the rear tyre needs when accelerating on a straight.

I'm not sure why the question even needs to be asked...

Here's my confusion then. If you mount a tire so the outside label is on the outside of, lets say the left wheel, and the tread arrow is pointing up as you look at it from the front of the car, then the right tire needs to be rotated 180 degrees so the "outside" label is on the outside of the right wheel and the tread arrow is going to point down, no?

I missing something here.

TIA
Miguel

Tyres on a four-wheeled vehicle don't lean over when cornering... the tread doesn't necessarily have a direction. Nor do some m/c tyres.

Dont ya fit it so the arrow points the direction of rotation ? All 3 of mine are fitted so the direction is the same n any rim can go on any wheel ..... never buy them directional ones or the spare can only be used on front or back .... not very convenient .... I know you don't have a spare so this is bollox to you lot 😉

There are Directional and NON Directional Tires.

Why? As long as it squishes away from the line of contact, what difference does it make?

And why does the rear tyre not need to displace water in the same way?

I have noticed that the treads are reversed for "pushed" and "driving" wheels on motorcycles. I can't say why.
Directional tyres on 4-wheelers are meant to improve water dispersion from centre to outside. They must also be rotated on the same side of the vehicle only to even out tread wear. Spare tyres cannot be directional tread patterns.

As I recall-which is from a old brain and many years, etc.,

the opposite is true for water-it is desired to have a means for the water to be thrown outward away from the area that traction is desired. Rain grooves also allow the tread to hold a certain amount of water in motion then various tread features allow it to escape. Pictures of tires running in water show that the tires (scary indeed!) are actually floating on water as we drive or ride. NOT! touching the pavement.
Scary concept. I once hydro planed a newish 1966 MGB @ ~ 75 mph on a concrete interstate I-70, wide sweeper in a heavy rain and instantly was in the grassy median having turned in a few circles. When that precious little traction breaks, all hell breaks loose. Modern tires have much better water dispersion. Think about race tires and often slicks.
When we took delivery of our new 2013 BMW X3 in Dec 2012 at the BMW Performance center in SC, one of the options was to drive the wet pad, a circular pad thats flooded and to learn how to handle the car in heavy water. It was amazing to experience and a great learning thing. My wife dislikes that sort of thing but did ride along on the slaloms and other fast tracks except the ride at speed with a pro driver at the wheel which she also took a rain check on. She did the off road track too. I have not done their MC program there. Our "delivery guy" who stays with you through the whole process most of the time is an off duty LEO who normally does MC training but was filling in with cars our day.

The dynamics of a PTW are far different than a 4 wheeled vehicle and the front tire/wheel plays a different role in that scheme. Now a physics expert can take over the discussion...

My slick bicycle tyres have direction arrows.

Discuss.

Jimc- tires on a car or truck DO! lean. It's an aspect of suspension geometry and if not then cars would be like the little red wagon or a horse buggy.
More happens than just the car leaning.
But as you say, it's a much different dynamic than PTW's.
Tires also benefit in doing their job from highway profiles which if well done lets water off and promotes handling in curves.
I have puzzled about the fact that driving practices are "wrong sided" in some parts of the world, yet cars are built with steering wheels on both sides, why couldn't they be more finely tuned in steering and suspension, if all were the same?
Not pointing fingers here, but to not buy directional tires for rotation is archaic?

Likely is due to the carcass construction-the part you don't see.
BTW, who decided they are tires, not tyres?

I think tyres is British (and ex-commonwealth) and tires is American. Scanning through a few of the previous posts here seems to support this (but there are always exception).

Now I suppose we have started an interminable discussion about spelling. It is all Kantuckid's fault.

My question is why did it change in US lingo? After messing with ( a great way to put it!) British cars for some years, I know most all that way of saying things wheeled, that is.

I'm tired. Are you tyred?

Noah Webster and the American public school system.

FWIW: the word tire or tyre is a holdover from the days of wooden wheels. The rims of which were made from several sections, usually one per spoke. They used no glue, pegs or other fasteners to hold them together. An iron band surrounded the rim sections, holding them together. It was made slightly smaller than the rim sections, heated in a fire until it expanded enough to slip over and shrink while cooling, tying the whole assembly together.

I would bet money that no one, even an engineer or professional rider would be able to tell by riding if the tires were mounted correctly or backwards without looking at the tread or sidewall.

What matters is not "can whomever tell it's backwards" but rather does it keep someone alive by doing the job as it was designed. I suspect pro riders have a very fine feel for whats right or not but then those tires are much different in tread appearance too. Engineers would use data gathered for analysis unlike a pro rider/driver. The tire engineers I worked with did not drive or ride anything, except to get to work.
Tire engineer story of the day: While at Goodyear/Topeka Plant, I sold my 65 Shelby Cobra Roadster to an engineer there with whom I'd gone to HS. He traded me his Mustang 2+2 towards the sports car. Michelins on the Cobra, GY's on the Ford.

So the OE tire on the front of my Vespa is not backwards?
It makes sense now the "V" should be pointing up to prevent slip when braking.
Hence, the front wheel does 75% of the stopping,.
Thanks for the insight. Makes sense.