I’ve got a pair of SK gravel Kings, mounted on vittoria elusion disc alloys, with about 4,500k on them.

Initially set up tubeless by the shop, they were running fine until over the last month I’ve (on separate occasions) put 3-5mm cuts on the shoulder of each tyre. When I did the first one I realised all the sealant had dried up, and whilst replacing that switched both valves for Milkit ones (so I could inject sealant – the ones supplied initially wouldn’t let the tube through) and the MilKit sealant. Both holes have been repaired (by me) with slugs/worms/bacon strips and I’ve managed a 120k ride on the repaired rear without issue.

I now cannot for the life of me get more than 20psi to stay in either wheel. They’ll sit quite happily at 45 on the stand, but 10 minutes into a ride they’re back down to 20. The air seems to be escaping very slowly from either the repairs or the valve.

Should I persevere with tubeless or go back to tubes? For the first 2,000k those tyres ran fine with tubes on a different set of rims, but I’d prefer to stay tubeless as (on my MTB at least) I have a predisposition towards pinch flats. There’s every chance that I’m just an inept mechanic, although I switched my MTB to tubeless myself last year and it’s been running perfectly.

All suggestions welcome!

Andy

For the first 2,000k those tyres ran fine with tubes

You get 2000km out of a set of mtb tyres? Blimey.

It’ll be the valves – reseat them (or even a dab of silicon sealant where they touch the rim tape).

Way too much faff. Stick some tubes in and stop wasting your time.

I’ve found the gravelkings work really well tubeless so if they were ok before your repair and valve change then it’s probably one of the two causing the air loss. You can try to test for leakage using the old classic soapy water bubble check.

If it’s the repair and you can’t improve it or patch from the inside then maybe run them with tubes until they die.

I would stick with it. New tyres, another 2000km of trouble free riding.

Saying that I gave up on tubeless on 28c tyres as it just didn’t really work as punctures didn’t seal as well as on lower PSI MTB tyres. If I had got 2000km without any issues I wouldn’t have given up on it.

with about 4,500k on them.

I’ve (on separate occasions) put 3-5mm cuts on the shoulder of each tyre

They sound like they’re knackered. Buy some new tyres.

Get a bottle to spray a soapy solution around valves, tyres, rim/bead.

You will soon find the leak.

(Old spray bottle from household cleaner is perfect).

You will soon find the leak.

There are cuts on the shoulder of the tyre. It holds air if it’s parked, but loses air if it’s ridden. Safe bet is that the flex of the tyre when it’s ridden is enough to prevent the sealant from sealing the cuts.

The leak is a steady gentle bubbling hiss from either the repair or the valve. I can make it stop in the stand, but out riding it must be opening up.

I didn’t have a figure in my head for the longevity of tyres, but looking back at an old road bike (hooray for strava gear records) I’d been swapping them out around every 5000k, so I’m less put out about putting new ones on. If the vales don’t seal, I’ll stick tubes in the old ones and run them into the ground, as there’s still good tread away from the centreline of knobs.

Any reasons not to put a new set of GK SKs on? I’m commuting 80% on roads, with occasional more adventurous rides into the cairngorms.

with about 4,500k on them.

I’ve (on separate occasions) put 3-5mm cuts on the shoulder of each tyre

They sound like they’re knackered. Buy some new tyres.

Yeah, my thoughts exactly. Some tyres will run on a lot longer than that, but I wouldn’t expect it from a “high performance” tyre.

My guess is that it’s the valves, although if the slashes are at the edge of the tyre then not much sealant will reach them.

Yeah, new tyres, tubeless sorted.

I stupidly removed one of my road/gravel tyres to stick a patch on a small hole… Tyre went back on really easily and now won’t seal – I reckon they stretch, so once removed are only fit for the bin (or a tube, but I’m not that desperate! Well, actually, I don’t think I have any tubes 😆 )

I reckon they stretch, so once removed are only fit for the bin

not my experience. I’ve swapped tubeless tyres around a few times and the GK SK re-seat very easily but it may depend on the tyre.

Any reasons not to put a new set of GK SKs on? I’m commuting 80% on roads, with occasional more adventurous rides into the cairngorms.

If they are working for you then why not. I use them but my riding is about 60:40 gravel:road and gravel as in bridleways and old rail lines. I would choose something knobblier for a more off-road bias or smoother for road but they do the job well enough.

…and did you know you can get them in fancy colours too?

One of my GP4000 is now dead, with a sidewall tare, the other is looking worn. Thinking of trying tubeless for the first time with a pair of Hutchinson 11 All Season or Performance.

Put a mushroom patch in the tyre as a proper permanent repair.

I could never get my GK slicks to reseat properly a second time if I had to remove them for whatever reason.

Might be different on other brands of rims perhaps but the GKs did seem to stretch in use.

not my experience. I’ve swapped tubeless tyres around a few times

Road?
MTB are fine (lower pressures I guess) – but I’ve had Schwalbe and now a Spesh road tyres that are much looser fit on the bead than when first fitted.

I found last night why my Spesh tyre wouldn’t reseal – dried Stans on the bead. Gotta pick it all off with a thumbnail (never found anything else that works as well!). Little lumps and nodules of sealant giving the air a place to escape. Hoping removing this’ll negate the need for a new tyre.

If the new tyres don’t fix it it’s worth checking the tape. I had a slow air leak because the (4 year old) tape had started to lift so air was escaping from the spoke holes. I discovered it with soapy sprayed water.

It’s one a dem proper UST tubeless Mavic rimz, so no tape. 🙂

^I was replying to the OP…

I did wonder 🙂