Having just decided to persevere with the old K81's rather than try out Avons this time, I discovered what appears to be a delamination in the tread of one of my existing tyres. The hole can clearly be seen on the pics and is currently on the back of my Commando these last two years. You can see the carcass of the tyre through the hole and it is possible to slide a probe under the tread a few mm along the tyre, without resistance both forward and backward. I've never seen this before on one of these tyres - but it is certainly disappointing. I could imagine this quite easily resulting in a real blow out on the road, with God only knows what results.
I was going to put it on the front (!) and buy another new one for the back. Having now seen I need two new tyres I think I will go for a pair of the Avon AM26's after all!
Hmmm, that's nasty, looks like the tyres would eventually split in half down the centre seam.
K81s became TT100s back in about 1970. How old is this one?
attached is a photo of my 13 month old Avon Roadrider 100/90V19, which has now been replaced by warranty.
Maybe they are "New old stock"
Check the date of manufacturer?
the Avon Roadrider AM26 photo in my post above was fitted in spring 2012 and failed in Autumn the same year.
Date code on side wall was 4710.
47 = week 47
10 = year 2010
So not new old stock in my case.
A roadrider from 2010 is prior to a re-vamp of the tyre in 2012. For a period of several months the 100/90 - 19 roadrider was not produced or available to fitters.
Any roadrider prior to 2012 is likely to have these defects.
thanks for that info, it explains why more recent Roadriders I've used have been defect free.
My duff tyre is a Dunlop Roadmaster TT100, but also bears the K81 identifier. It was made in France and carries a date stamp of 4015, which I assume means wk 40, 2015. It was probably fitted to my bike in early 2017 and has only done around 2000 miles! I think the nature of failure is some kind of disbond between tread and carcass which seems to extend about 4cms along the circumference. I can imagine this chunk of tread ultimately being flung off the tyre at maximum speed if I had not spotted it. Interestingly enough my local bike mechanic who is an ex police motorcycle mechanic, reckons its not the first of these tyres he has seen in this condition!
I don't suppose Mr Dunlop would be interested, but it certainly is a reminder to all to check their tyres for damage!