Trials Australia Forums

I was doing a bit of tyre changing the other day and the one coming off (a 2002 Michelin tube-type XII rear) felt a bit heavier then the one going on (a 2006 IRC tube-type rear). I decided to weigh them and was amazed at the difference:
2002 Michelin XII tube-type rear 5.3kg
2006 IRC tube type 4kg
Thats a 1.3kg reduction in unsprung mass just by changing the rear tyre (they are both equally worn ie they have both lost their sharp edges) - gotta be the cheapest weight reduction of a bike I've ever seen.
I thought that maybe the weight difference is due to the age difference of the two tyres??? Do tyres get heavier with age??? Any ideas??

More than likely something to do with carcass construction.... Does the Michie have heavier/stiffer side walls than the IRC ?
Might be a 6ply v 4ply thing ???

I went and had a look for clues in the plies department
IRC tyre (the light one) is marked "4 P.R."
Michelin (the heavy one) is marked "2 polyester plies"

I'm just in the middle of fitting a new IRC on the back of my Ariel and took note of how light it is compared to the old Pirelli...
David,do you have any other suggestions for massive weight loss on an HT5 ?

Jon you have me wanting to weigh a very old front trials tyre that came off my M49 Bultaco when I bought it. I remember the tyre felt quite heavy when it came off and I just couldn't throw it away. It has the vee pattern knobs like you can see on the sales brochure shots of 1960s Bultaco trials bikes. I'll weigh it on the weekend. Not saying your Ariel has 45 year old tyres its just as a matter of interest

That tyre was so hard it could well have been 45 years old ! With new wheel bearings and a new tyre all I have to do now is make new footrest mounts and rear brake lever. Then it should be ready for a day of schooling by Mick Andrews tomorrow.

Mick Andrews school?

I just checked out that old front trials tyre and it is a Firestone made in Spain

Old Firestone front trials tyre 4.8 kg
New Michelin front trials tyre 3.6 kg

I suppose the new ones must be "lead free" !!!
Mick Andrews is coming down to us for a day of schooling,organised by a mate in our club who knows him. Should be a day out to remember,plus learn something if possible...