Hello all,
Well I had not thought about this until the other day when, well, it
felt like I had run out of grip and slid a bit. Sure I was pushing just a little, but...

My question is this : My bike has just 2500km's from new and the
tyres still have plenty of life in them.

BUT ! : I bought this 312 'new' old stock, so the tyres have been on the bike in the showroom for perhaps 2 years or so...

Would they have gone 'off' and thus the slide or lack of grip?

Should they be changed after this amount of time irrespective of
klm's travelled?

Thanks,
Matt

A friend had a crash earlier this year on brand new tyres and couldn't figure out why (he was a competent rider who has had a wildcard entry into the WSB a few years ago). On investigation he came up with the following.

Tyres have a manufacture date on them and an unofficial use by date. An internet search will reveal that m/c tyres has less than 1/2 it's grip after 4 years and should never be used after 6 years.

The manufacture date is:
look for the letters 'DOT', then look for a number series at the end. The first two digits indicate the week of the year the tyre was manufactured and the last two indicate the year.

for the sample below the tyre was made in the 27th week of 2007

Attached Images

 

Good answer.

Emmevi beat me to it.

It's likely the tires are old and need to be replaced for optimum grip.

Wow thank you guys for these posts.

I never knew that...

Rubber, a major component of tyres looses about 15% of its properties every year. Therefore a tyre, without moving an inch, is 45% less effective in respect of the rubber content after three years.
Not sure how ageing affects the synthetic and other additives in a modern tyre, but the above is worth thinking about.
Hot/cold cycles are said to be not important in a modern road tyre.

Great post/info... Thanks
Although I knew tyres degrade over time with out even being used, I did not know the annual rate of this degradation is around 15%...
I'm sure this info will be handy to a lot of us. Especially those with multiple bikes that don't do many Km's/miles per year.

Thanks again.

Well hell. I just put 3 year old tires on my bike that came with the bike stock but were changed out with 600 miles on them. Now im gonna be worried every time i ride. but i am slower than shit so i shouldnt have any problem.

Last time I changed tires was during the Pilot Power 2CT front tire recall. When was that again?

I've found that a more track biased tyre "went off" before I considered it worn out. The tyres were Pirelli Super Corsa's and by the time they were half worn they were becoming hard to get heat into and basically didn't offer anywhere near the same grip as when they were new. I've heard that the track focussed tyres can't handle too many heating and cooling cycles, so maybe that was part of the problem. Since then I've run 50/50 road/track tyres which have provided consistent grip to the end of their service life.