Tyres on the wrong way for over two years

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riddly

New Member
I just took delivery of a hybrid bike with the tyres on both ways - front chevron facing backwards.
Obviously that’s unlucky, as that’s the tyre that hit the blackthorn after 30 miles.. six bloody punctures.
So much for Kevlar, they’re both facing forward now.
 

riddly

New Member
I've never paid any notice of those arrows. As you say, no discernible difference, not for a road tyre anyway. I imagine it would make a difference on a tyre designed for mud.
Don’t mud tyres have non-directional knobbles?
 

Red17

Veteran
Location
South London
Not all. I run Challenge Limus tyres on my cx bike which Challenge website say are directional (the knobs are arrow shaped rather than square)
 

Globalti

Legendary Member
It's all cobblers dreamed up by marketing types in an effort to add value to their tyres. The only possible reason for a direction arrow is to ensure that the brand name of the tyre goes where it should be, on the right. Some tyres, Veloflex for example, only have the name on one side.
 
There is a purpose to having tyres with ‘tread’ on the shoulders ( it’s not tread, it’s not there to enhance grip, or move water ) with the arrow pointing in the correct direction. It’s there to make sure that the manufacturers ‘power’ spec is applicable. The Q.A. compliance people don’t like it if a tyre’s spec can’t be matched in the real world. The ‘tread’ is an aerodynamic / fluid dynamic device, to ensure any aero drag caused by the tyre is minimised. Air against air / water against water is less draggy than rubber against air, or rubber against water, so the ‘tread’ is there to trap air / water as the tyre rotates, which reduces drag, and gives the manufacturer something which helps them ‘prove’ their figures. With a slick tyre the arrow points so that the tyre rolls in the direction that the tread was laid onto the carcass. The boundary between the carcass and the tread is not actually perfectly uniformly flat, it’s ever so slightly ‘pear shaped’, in order to keep the tyres performance as ‘per spec’ the tyre should roll from the bulb to the tail, on each rotation ( this is also the case with ‘patterned / treaded tyres, but the pattern overrides the tread / carcass interface issue with patterned tyres) All of this is of little real world consequence, but compliance / Q.A. are a pain in the butt, and need stuff like this to keep them quiet.
 

Globalti

Legendary Member
So at 20 mph a small part of your tyres is hitting the air at 40 mph? And they are trying to make them aerodynamic?
 

Ajax Bay

Guru
Location
East Devon
it has the same effect as the dimples on a golfball
There is a good deal of quality science and practical testing behind the benefit of dimples on a golf ball. Less (vanishingly less) behind the 'come again' post above.
"the manufacturers ‘power’ spec" - examples?
"the ‘tread’ . . . gives the manufacturer something which helps them ‘prove’ their figures." Assume these figures are the aforementioned ‘power’ spec figures.
So at 20 mph a small part of your tyres is hitting the air at 40 mph? And they are trying to make them aerodynamic?
The top of the front tyre is moving at 40mph but not sure there's any "trying" going on (see quote below). Why not make them as aerodynamic as possible? The best way to do this is to have an 'overhanging' mudguard (I have read) - not UCI legal, I suspect.
From the mag in 2017:
"According to Continental, the aerodynamics of the GP4000 “wasn’t a design feature, but the shape is good and the tread gives micro turbulence as a 23mm on a wider rim”. It would appear that the observed aerodynamic prowess of the Continental GP4000 is down to serendipity."
If the patterns (as rr says (truth smuggled in) "it’s not tread, it’s not there to enhance grip, or move water") on the Continental tyre shoulders have any aero effect (delaying the transition from laminar to turbulent air flow), I suggest they will work just as well which ever way round the tyre is fitted. I wish there was well-founded research on this but yet to find anything (I have looked).
 
Location
Loch side.
There is a purpose to having tyres with ‘tread’ on the shoulders ( it’s not tread, it’s not there to enhance grip, or move water ) with the arrow pointing in the correct direction. It’s there to make sure that the manufacturers ‘power’ spec is applicable. The Q.A. compliance people don’t like it if a tyre’s spec can’t be matched in the real world. The ‘tread’ is an aerodynamic / fluid dynamic device, to ensure any aero drag caused by the tyre is minimised. Air against air / water against water is less draggy than rubber against air, or rubber against water, so the ‘tread’ is there to trap air / water as the tyre rotates, which reduces drag, and gives the manufacturer something which helps them ‘prove’ their figures. With a slick tyre the arrow points so that the tyre rolls in the direction that the tread was laid onto the carcass. The boundary between the carcass and the tread is not actually perfectly uniformly flat, it’s ever so slightly ‘pear shaped’, in order to keep the tyres performance as ‘per spec’ the tyre should roll from the bulb to the tail, on each rotation ( this is also the case with ‘patterned / treaded tyres, but the pattern overrides the tread / carcass interface issue with patterned tyres) All of this is of little real world consequence, but compliance / Q.A. are a pain in the butt, and need stuff like this to keep them quiet.

Barman! I'll have some of what this chap is drinking.
 

Ming the Merciless

There is no mercy
Location
Inside my skull
There is a purpose to having tyres with ‘tread’ on the shoulders ( it’s not tread, it’s not there to enhance grip, or move water ) with the arrow pointing in the correct direction. It’s there to make sure that the manufacturers ‘power’ spec is applicable. The Q.A. compliance people don’t like it if a tyre’s spec can’t be matched in the real world. The ‘tread’ is an aerodynamic / fluid dynamic device, to ensure any aero drag caused by the tyre is minimised. Air against air / water against water is less draggy than rubber against air, or rubber against water, so the ‘tread’ is there to trap air / water as the tyre rotates, which reduces drag, and gives the manufacturer something which helps them ‘prove’ their figures. With a slick tyre the arrow points so that the tyre rolls in the direction that the tread was laid onto the carcass. The boundary between the carcass and the tread is not actually perfectly uniformly flat, it’s ever so slightly ‘pear shaped’, in order to keep the tyres performance as ‘per spec’ the tyre should roll from the bulb to the tail, on each rotation ( this is also the case with ‘patterned / treaded tyres, but the pattern overrides the tread / carcass interface issue with patterned tyres) All of this is of little real world consequence, but compliance / Q.A. are a pain in the butt, and need stuff like this to keep them quiet.

So by having tyres on the wrong way round the fabric of space time is unravelling or have I misunderstood?
 
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