Swapping tyres around, and scrutineering!

[KatieMsidecar]

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

[ChrisWells]

In a pinch I would be tempted to turn the chair tire around (assuming you have more wear on one edge than the other). Techincally Avons (I guess I'm assuming the chair is an Avon) are directional but I would think that is a lot more important on the front and rear where the forces are greater (and if you think about it the rear brake acts on the rear tire in the same way the chair brake would on a reversed chair tire). I would definitely try that before resorting to a tire that was an inch narrower.

As for handling differences I would think the threshold at which you would encounter 3 wheel slides and/or power over-steer in right hand corners would be slightly lower if you mount a 1" narrower tire. Should be no difference in left hand corners (especially based on your avatar photo . In a straight line you might be a fraction of a second faster depending how much toe in you run on the chair wheel.

Another option is to ask around for cast offs at the track (or check the dustbin at the track). I currently give away most of my cast offs with about 1/4 to 1/3 of the wear holes still showing (my F1's handling seems to deteriorate quickly if I run my tires for more than 2-3 weekends).

Chris

[kew]

You wont have a problem using a 6" on the side, that's what I use.
The problem with using a front tyre is that it will be a softer compound.

[Jo Warriner]

I wouldnt pass an outfit with a tyre on the wrong way round.

[ChrisWells]

I wouldnt pass an outfit with a tyre on the wrong way round.

Can you explain why, specifically referring to an Avon chair tire?
Does the chair tire transmit more braking forces than the rear?

[kew]

I and most other sidecar racers changed tyres around if they showed more wear on one side than the other, we did it for years.
A few years ago the scrutineers at the TT got hold of an Avon technical leaflet which showed the recommended way to fit the tyres, from then on scrutineers would not let anyone run with the tyres the other way around.
There is not a safety issue if the tyres are fitted the wrong way around but now that there is a leaflet showing a recommended direction we are forced to comply. (health and safety you see).
What Chris says about the drive and braking forces on the back tyre is absolutely correct.

[Jo Warriner]

As kew says.

Unfortunately, the world has become such that the question in my mind would have to be how could I explain to the coronor of inquests why I ignored the advice of the tyre fitting company.

[G JONES]

I wouldnt pass an outfit with a tyre on the wrong way round.

Hi - a few years ago - I would have agreed with you - BUT - a couple of years ago - I had a lengthy phone conversation with one of the staff at Avon Tyres - (I won't mention any names - but you all know him) particularly about the subject of swapping tyre direction - to cut it short - the advice was that the tyres when new should be fitted in the correct direction - but that once they have done a couple of meetings - it is quite safe to change them over...(I did get a technical explanation about things happening to the tyre after they are used for a while - we'll leave that )
Whether you'd get anything in writing from the maker is another matter....

[kew]

As kew says.

Unfortunately, the world has become such that the question in my mind would have to be how could I explain to the coronor of inquests why I ignored the advice of the tyre fitting company.

Jo is quite right, now that Avon have specified the recommended direction everyone must fit them that way around 'cos if there is a problem the scrutineer will be sued for a million pounds.
I accidentally fitted one the wrong way round at the TT and I did 2 practices before I was caught, I feel really lucky to be alive.

[G JONES]

Jo is quite right, now that Avon have specified the recommended direction everyone must fit them that way around 'cos if there is a problem the scrutineer will be sued for a million pounds.

Just a thought - don't we sign away most of our "rights" when we sign the entry form ?
Here's one I signed recently....

Acknowledgement of the risks of motorsport:
I / we understand that by taking part in this event I / we am exposed to a risk of death,
becoming permanently disabled or suffering some other serious injury and I / we acknowledge that even in the event that negligence on the part of the ACU, the promoter, the organising club, the venue owner, or any individual carrying out duties on their behalf were to be a contributory cause of any serious injury I / we may suffer, the dominant cause of any serious injury will always be my voluntary decision to take part in a high risk activity.
I have read the above and acknowledge that my participation in motorsport is entirely at my own risk.

[ChrisWells]

Getting back to Marianne's original concerns:

a) You can run the chair tire until one set of wear holes disappear completely (where a set is composed of those located "around" the tire, rather than "across" the tire).

b) You could swap in your ex-front tire (mounted in the same direction ) and you will likely notice little or no change in handling, however the tire will probably wear faster than the old chair tire (assuming the current tires have the usual differences in compounds) so keep an eye on it.

c) Depending on who is scrutineering your next meet you may get away with turning your chair tire around (if that helps with your wear pattern).

d) Post in wanted for a 7.2 chair tire with a bit of life left in it to tide you over until you can afford a new one.

Hope that helps.

Now back to all the tangents we were off on...

[ChrisWells]

I accidentally fitted one the wrong way round at the TT and I did 2 practices before I was caught, I feel really lucky to be alive.

And that was a rear tire
Which got re-mounted the opposite way and sent right back out for another practice (where it didn't fail either).

[kew]

Acknowledgement of the risks of motorsport:
I / we understand that by taking part in this event I / we am exposed to a risk of death,
becoming permanently disabled or suffering some other serious injury and I / we acknowledge that even in the event that negligence on the part of the ACU, the promoter, the organising club, the venue owner, or any individual carrying out duties on their behalf were to be a contributory cause of any serious injury I / we may suffer, the dominant cause of any serious injury will always be my voluntary decision to take part in a high risk activity.
I have read the above and acknowledge that my participation in motorsport is entirely at my own risk.

[/quote]

Gordon it doesn't matter what you sign on an entry form you cannot sign your rights away. The ACU is spending lots of money fighting cases on behalf of their members and that will get worse in the future as even more people try to make a quick buck at someone elses expense.

[Kickaha]

We've swapped slick tyres on bikes for ages, makes no difference at all in handling , braking or anything else, we were told it's just do do with the tyre construction and the splice where they are joined and the direction of either the drive or braking acting on it

I've always thought reccomendations could be ignored especially reccomended speed signs

[G JONES]

Gordon it doesn't matter what you sign on an entry form you cannot sign your rights away. The ACU is spending lots of money fighting cases on behalf of their members and that will get worse in the future as even more people try to make a quick buck at someone elses expense.

So now I know where I've been going wrong all these years....
I've been (mistakenly) thinking that I'm responsible for my own actions - wish I'd known sooner - could have blamed all sorts of things on someone (anyone) else...
So the disclaimer we sign on entry forms is not enforceable ?....never really thought too much about it - if you want to go racing - you sign whatever you have to....