Was that with or without sealant?

That'd be normal on a TLR without sealant, but I agree it's not right on a TL either way.

Edit: duh, with, n.m. That's very odd with sealant. I see that on Corsa Speeds without sealant, but sealant fixes it right away.

I've seen this happen on other tubeless tires on the first (or first few) rides. Sometimes it seems like it takes a little while for the sealant to do its thing on a brand new tire. I wouldn't give up on that tire yet if i were you. Wait a few days and a few rides and see if it is all sealed up

I've seen this with other tubeless-ready tires; the Corsa Speeds are particularly bad. These TLR tires are not fully airtight on their own, that's why they require sealant, and it's why they're called 'tubeless-ready' rather than just 'tubeless'. It's also why they're faster than traditional tubeless tires that have an inner butyl layer. It's a tradeoff.

As the sealant works through the tire on the first few rides, they'll hold air better and better; but never as well as a traditional tire with butyl tubes. I found the Corsa Speeds to be only slightly better than latex tubes.You still need to pump before every ride if you want a consistent air pressure.

I thought GP5000 TL's had an additional liner so that they retained air even without sealant? This is why they weigh ~40g more than Schwalbe Pro One's for the 25c size.

This video is not inspiring.

Actually, that sounds familiar now that you mention it; you may be right. Usually tubeless ready means no butyl liner. If these do have a liner it must be really thin to allow that amount of sealant leakage. Wonder how much it slows the tire down compared to the non-tubeless version with latex tubes.

I’ve had no air loss issues with Schwalbe pro ones or zipps. I don’t think this is ‘part of the process’; TBH if that is, then I can’t help but think it’s an excuse for an unprepared product. I’m not prepared to wax another £50 ‘in case’ or scratch another ride because they’re sub standard. That was 2 hours with 2 inflations after 24 hours with them sealed and spun for a few minutes. If that’s not enough then conti have missed the mark, which is unlike them hence the post as - I hope - it’s just a bad batch. I’ll try them again... in a year or so!

I see this sort of leakage all the time in conti tyres i use on an MTB.
It seals up ok with sealant inside after a bit.

Strangely dont get it with the alternative Maxxix tyres I run. I think the side wall coating of rubber is thicker (and heavier) on tje Maxxis than the relatively thing and plyable Contis.

So part of the proper mounting process for a TL tire is to hold the wheel on its side, with the part away from your body slightly lower so gravity makes the sealant go there, then shake the sealant up and down to completely coat the sidewalls and beads, then rotate the wheel a bit and do it again, working around the whole tire. You then let the wheel sit on that side for like 15 minutes, turn it over and repeat for the other side. This seals the beads and also all the little holes in the sidewalls. Sometimes you even have to do both sides twice to get a really good seal. Did you do that part? Because otherwise that's totally normal behavior for a lot of TL tires.

Yup. Very common. Can take weeks for the sidewalls to seal up. After a couple of sealant applications the tires often hold air better than tubes.

But these are TL tires, not TLR tires. TL tires are supposed to seal completely without any need for sealant.

Seems pretty normal for almost all of the tubeless ready tires I have used on road, cross and MTB. Usually stops somewhere between 2 and 7 days

I'm a broken record. The Conti 5000 TL is not advertised as a TLR. It's advertised as TL.

I know what you are saying, but that just doesn't matter in real life on seven different types of tires from four manufactures in my experience. No sealant=leakage. They all need some sealant to work well, regardless of what you are saying.

Also, on the Continental webpage installation video, they suggest using 30-60ml of sealant on the first installation for this tire, so there is that right from the manufacturer. They do not specify future sealant, but on initial install, they do.

I've had a different experience. Though it's dumb to run tubeless without sealant, in my tests every "TL" has held air perfectly well without sealant (I test them for a couple days before I dump the sealant in. This includes the Goodyear Eagle and Hutchinson Sector. And several gravel tires.

A couple of the GP5000 TL reviews I've read also said the tires hold air without sealant, including this one that said they held 90 PSI for 24 hours, which is less leakage than latex tubes.

I think there's a possibility the OP's tires aren't to spec.

That's possible. It happened to me on a pair of tires. One was perfect and one oozed sealant. I figured the oozy one was a return, had been ridden a little and sustained some sidewall damage. After a couple of weeks it sealed up fully and I'm still riding it without a problem.

Wow. If it’s this much trouble to get tubeless tires ready to go, I think I’ll stick with tubulars and glue

It's not trouble. You just mount like a clincher, add a squirt of sealant, then inflate. It'll ooze slowly a couple days (the same as letting the tubular dry) and then be ready. I'll use a oozing MTB tire almost right away.

TL or TLR, I'd never run without sealant. Sealant is what makes tubeless so good in the end.