My understanding is that the plies in tyres are laid up in certain directions. The plies overlap and are more likely unlap depending on which direction the major tangential force is applied. If a tyre is subjected to braking forces (usually greater on the front) the force is pushing the plies in an anti-clockwise direction when viewed from the left. When the bike is accelerating the forces through the rear tyre are applied clockwise viewed from the left. That is why tyres and arrows are marked so you can get the preferred direction correct for front or rear fitment. Some tyres are universal for rotation.
Tyre Direction Arrows
- Thread starter BigEd
- Start date
Was this the case back in 1947? or is this arrangement a modern 'development' if it was so back then (which I doubt) did the Phils take it into consideration with the introduction of the design feature?
remember.. we are working with 28 BHP, not 280
That might be the case, but the police might notice the recommended direction of rotation when the bike is parked. Worse still would be if a machine was involved in an accident and an insurance assessor noticed it.
I had an accident 25 years ago on the Rapide which was a major blowout of the rear tube at 70 MPH two up on the M5, which at least deposited us on the grass embankment and not the middle of the motorway. The first thing the insurance assessor did when coming out to look at the bike was look for the tyre rotation arrow to check it was on the correct direction, which it was. The assessor said at the time approx one in 10 of bikes he assessed after accidents had tyres fitted that were wrong direction which leads straight to the insurance company walking away and saying the bike wasn't covered as it wasn't road legal due to improper fitting of the tyre.
As we all know, if an insurance company can wiggle out of a claim then they will do.
Simon
Thanks Simon,
I was alluding to that being the case, but without thankfully being able to back it up with an unfortunate incident like yours.
Cheers
David
I was alluding to that being the case, but without thankfully being able to back it up with an unfortunate incident like yours.
Cheers
David
Well there is something for the Club to follow up with the tyre manufacturers its too good a point to loose. As the years go on and perceived technology and our bikes design move apart, there are more and more items like this (eg tapered wheel bearings and rim wobble) that need professional clarification.
I am in solid agreement - especially when one of the design features of our bikes is the inbuilt ability to [quickly] reverse the rear wheel at the roadside in order to change final drive ratios to suit the terrain. As I mentioned earlier, I have a 48 one side and a 50 the other.
In a like vein - I wonder if there are there any modern tyres, 18 or 19 inch that fit Vincents that do not have directional arrows?
BTW I notice that very few (none?) car tyres have directional arrows.
I think these days the directional arrows are much more to do with the way the rain grooves are oriented that the way the carcass is built.
After breaking a rear drum, drive side, just south of Margaret River in WA I ran the rear tire (modern Avon - well not so modern now - Super Venom 120/90 - 18) across the Nullarbor two up with a full luggage load in some pretty serious heat and into Adelaide before getting a new drum and putting things back the right way around. No issues arose, in fact I hadn't even thought about it until now some 13 years later
After breaking a rear drum, drive side, just south of Margaret River in WA I ran the rear tire (modern Avon - well not so modern now - Super Venom 120/90 - 18) across the Nullarbor two up with a full luggage load in some pretty serious heat and into Adelaide before getting a new drum and putting things back the right way around. No issues arose, in fact I hadn't even thought about it until now some 13 years later