Swapping tyres around, and scrutineering!

[David Stewart]

The Technical Official is NOT responsible for the safety of the machine and tales of individual technical officials being liable personally for millions of pounds are nonsense.

"9. TECHNICAL INSPECTION.
Unless otherwise stated, inspections will take place from 07.30 on the morning of the event. Machines will be checked for eligibility and the competitors clothing and helmets will be examined, competitors must be present. It is the competitors responsibility to ensure his/her machine complies with the regulations and is safe for competition. However, a Technical Official may refuse to verify a machine on grounds of eligibility, lack of cleanliness or safety.
Any machine involved in an accident must be re-inspected."

The Road Race Committee insist that wording is inserted in all Supplementary Regulations (ours above is just one example of what is acceptable) to reinforce this. Every rider who has undertaken a CTC Course will also have had to answer the question:-

"Who is solely responsible for the safety and compliance of your machine?" if they don't answer correctly, they don't pass the CTC test. Those papers are kept as a 'disclosable document' in the event of any future claim. I know that doesn't neccesarily help when dinosaurs like Keith, Gordon or myself who are far too old to have ever taken a CTC Course, but it is the firm basis of how the ACU solicitors, insurers and barristers deal with any claims of that kind.

Spinning tyres is a different subject altogether. In most instances with modern construction radials there is absolutely no safety issue with it, but you guys still use a lot of bias-belted cross ply stuff (which is why the market is so small & expensive). There is some evidence that splice joints, although a lot better than they used to be, can still cause problems every now and again. I worked in the Goodyear Technical Research Centre in Luxembourg for a while and this was something they were working very hard on back in the early 80's - mainly due to the proliferation of assymetric tyres rather than uni-directional stuff. Michelin also did a lot of work on it at Clermont Ferrand at around the same time (with more success than we had) as they were looking to replace their XVS & XAS assymetric range.

The manufacturers have a vested interest in seeing radial motorcycle tyres used only in one direction, but in the modern world they stop short of saying it's dangerous and merely say it's not recommended. Sign of the times I guess.

[Rent-a-Ballast]

Tyre arrow direction on slick tyre relates to drive direction so only rear wheel is driven if you look rear tyre arrow forward, where as front wheel arrow backward

[David Stewart]

Darren that's only applicable on bias-belted tyres and is due to the angle of cut on the splice joint (we've been through it before on here somewhere).

Radials are never marked as bi-directional.

[kew]

All right, all right, Dave is correct in everything he said but I believe that it is OK to turn tyres, even cross ply tyres.
When I mentioned the scrutineer being sued I was being somewhat facetious.
I'll go home now.

[Lisa]

Personally I would not put a front on a side.
We did this once and it only lasted one race due to the wall is softer on a front tyre than a side tyre.
I would ask around if any one has a used side tyre that still has some life in it.


We went out in practice for 2 nights with the front tyre in the wrong way, until Jo spotted it
But Mark said he reckons the sidecar rode better with the front the wrong way round

[flexford]

We have managed to afford new front and rear slicks, which on my 1996 Baker are 6.2 and 8.2 respectively. We can't afford to replace the sidecar slick which is a 7.2. It is really worn, so that some of the wear holes are in danger of disappearing. The front is a bit less worn than the sidecar (you can see the holes!) but is smaller.

Would it affect the handling if we fitted the cast off front to the sidecar wheel, making it 6.2 instead of 7.2?

(Am I a numpty?) This sidecar game is such a learning curve when you come into it with no knowledge whatsoever!

The scrutineers haven't yet commented on the state of the tyres, but when the holes have gone, will they reprimand me? (They've reprimanded me for lots of other things, but always "say get ..... done before I see you again!)

Marianne

Marianne, PM your address to me and we'll send you a 7.2" down ... it'll have done us but just the race week of the TT and Cadwell ..... it wouldn't do us at a British round but it'll be 1000% better than what you have

[flexford]

Just a couple of extra points (I've edited this as I had written it on my phone last night and it did seem rather casual):

Re running your tyres around the wrong direction, on the chair and the front (if they are Avons) don't worry about the performance too much (if you really don't have a choice), I can't comment about Yokos. I can say this with a little bit of reassurance, as Dave had a conversation with Steve Smith at Avon last week as our tyre man had put the chair and front on the wrong way (rotation) and as time was already tight to get them swapped he phoned Steve to check. With Avons its purely about the way they are joined "the seam" is set to work with the tarmac rather than the tarmac working against it. Steve assured us it would not effect performance (the boys were only 0.2 seconds of the lap record) but in an ideal word they should be fitted the correct way - however if you are doing a lot of meetings on the same set of tyres then ideally they should be the correct direction.

Re running a narrower chair, yes it will effect performance, a narrower chair wheel will break away a lot quicker than a wider job. If you're getting a 7.2 to break away then you'll find the 6.2 very lively

Hope this helps

PS. I haven't read all the posts so I apologise if I have repeated anybody else's comments

[kew]

Be carefull, although there is no problem with running tyres "the wrong way around", because Avon have issued the leaflet with their recommended direction of rotation scrutineers will fail you at a meeting if they are fitted the other way.

[G JONES]

Be carefull, although there is no problem with running tyres "the wrong way around", because Avon have issued the leaflet with their recommended direction of rotation scrutineers will fail you at a meeting if they are fitted the other way.

It might be interesting to understand why that could happen.
OK - the leaflet - I've not seen it - but I guess it's a print out of the "Fitment guide" on the Avon website - If we were to get "picky" - surely a "Fitment Guide" is just that - the recommended method when fitting slick tyres ? - rather than an "absolute requirement"

Surely a bit of common sense could be used here ? - as kelly says - they spoke to Avon - and were re-assured it was OK to run an "incorrect fitment" - we were told the same thing 2 or 3 years ago....

[steve-e]

Something I am in the middle of learning right now.. the scrutineer is always right

[G JONES]

Something I am in the middle of learning right now.. the scrutineer is always right

Don't get me wrong - I will never argue with a scrutineer - I appreciate what they do - they are the last line of defense between you & the track - I would rather they find something I have missed than find it myself on track.
However - if there is conflicting information coming from Avon - maybe the scrutineers are not aware that it is not 100% requirement to always fit their tyres according to the guide.

[Jo Warriner]

I can only speak for myself. I am aware of the fitting guide. And I am aware tyre fitters will tell you it's OK to run them the other way round. However, no tyre fitter will put that in writing. So, the only official line I have to work with IS the fitting guide.

The way I see technical inspection is this. The rider is responsible for the safety of their machine, as per ACU handbook. But I have a duty of care to the rider. I cannot, therefore, pass something that goes against written instruction from the manufacturer.

[kew]

I hate to say this but I agree with Jo.
Although it isn't a problem to run them in reverse the makers advise that they are fitted in a certain direction This is because it is the best way to fit them taking into account the forces excerted on the tyres during braking and accelerating.
They are not going to say that you can fit them in a direction which is not the best direction.

[Jo Warriner]

Are you feeling OK Keith? x

[kew]

Are you feeling OK Keith? x

Obviously not.