My hunch is that this isnt a problem. Tyres (carcass) are fairly rigid, and try to hold their shape - inner tubes are highly flexible, so would tend to squidge around a lump on the inside of the tyre.I wouldn't use a bit of old tyre as this may cause a bump in the carcass and strain the cut even more.
Repairing cut on outer tyre
Re: Repairing cut on outer tyre
Re: Repairing cut on outer tyre
It has never even occurred to me to fix cuts like this. I have never had any problem.
Re: Repairing cut on outer tyre
I am mean with tyres/run them into the ground with multiple cuts, but yes would always bin a tyre with a damaged sidewall.mumbojumbo wrote: ↑27 Mar 2023, 9:02pm Best to bin this but if you must retain ,line the inside with a denim offcut or a leather patch-it will minimise risk of hernia like bulge.
In fact when checking my driven into the ground tyres I always check the sidewalls - I am so mean that maybe the sidewalls may well "go" first".
I once rode a new somewhat delicate vittoria tyre over the Salter Fell Road - few days later on a long ride to catch a train back to London I was vaguely (I can be very vague) aware of a strange feeling on the front of my loaded bike. Looking at it back in London I discovered that it had the "hernia like bulge" you so eloquently describe. No idea how the bulge survived. Consequences could have ranged from disaster to at the very least missing my train back to London.
I also once years ago leading a ride London to Brighton had a sidewall blow at low speed with a great bang. Luckily happened close to home so was able to replace the tyre and we rode on.
So yep - would always bin tyres with sidewall cuts.
Sweep