Question Mavic Ksyrium Elite / Yksion Pro UST - tyre "aneurysm"

Apr 6, 2020
I bought a pair of Mavic Ksyrium wheels 25 mm (tyres included) and have to say I've been hugely impressed. Apart that is from the tyres...

A few months after buying them I noticed a huge bulge in the tyre wall of my front tyre. It was about 2" long. I thought I must have damaged it, so replaced it, only to find a week later that the back tyre went the same way. A friend who had bought a pair about one month before experienced the same thing with one of his wheels, though he'd bought from a different outlet. Maybe a bad batch...?

I took mine back to the shop - their only suggestion was that I'd over-pressurised it. I don't have an air-shot, just a track pump, so was sure this couldn't be the case. I therefore bought two more tyres, and a digital pressure gauge.

The digital pressure-gauge confirms the one on my track pump is very accurate. Since then, I've pumped the tyres up to 70 psi at a normal speed, then slowly take them up to 80-psi. I can honestly say that the tyre pressure has never gone above 85 psi (I weigh 85kg, so think that's about right...).

And this weekend, I get the same thing on my rear tyre. The tyres look as good as new, apart from the bulge. Whilst the tyre is as hard as you'd expect for one pumped up to 80psi, the bubble on the tyre wall is really soft. It's as if a very thin outer layer of the tyre has separated from the inner material.

I don't have disc-brakes...the brake blocks certainly aren't rubbing the tyre.

Is this a common theme with these tyres? If yes, then what's a better alternative (bearing in mind, these tyres were designed for this wheel).
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I think that 85psi is likely too little and the tires are getting damaged by the rim contacting the sidewall when hitting a bump. The pressure needs to be high enough to ALWAYS prevent rim pinching - regardless of the hype and science of lower pressure being more efficient because the tire 'rolls over' small bumps instead of bouncing.
Reactions: Cookster15
Apr 6, 2020
Interesting...I was erring on the lower pressure to prevent this bubbling, but I guess rapid deformation of a soft tyre wall may cause this sort of damage.

So, various questions spring to mind:
  • If I weigh 85 kg and I have a carbon bike, what pressure would one recommend for Mavic Ksyrium Elite wheels with Yksion Pro UST tyres? Same front and rear, or different?
  • I note that there's now Yksion Pro UST 2 tyres available....anyone tried them?
  • Were I to try a different tyre (though that would be going against Mavic's pairing of wheel to tyre) then what would people recommend (based on actual experience)?
I'd like to find the right answer about £50 a tyre, it's turning out to be an expensive experiment.
I only have experience with 'old school' road tires and rims. My method was to pump them hard.
And it might be that your troubles aren't due to pressure, but a defect in the tire. But if pressure is low enough for bumps to pinch the rim and sidewall, that's not good.

Apr 6, 2020
Yes, my first thought was a defect in a tyre, but I know of 4 tyres:
  • One that came with the wheels (bought NW England)
  • Two that came with the wheels (bought E England)
  • One replacement (bought E England, several months after the first)
If defects were that common, then surely there would be more noise on the internet? Mind you, we now have Yksion Pro UST 2 .
Check out the user reviews on the mavic tyres vs. continental tyres... Just switch to different tyres is my advice.
Not Hutchinson Fusions*, though. Or Pirelli ;)

Yeah. They arent that good. I took a set off a new Supersix.

*Hutchinson make the higher end Mavic and Pirelli tyres. The Mavic Yksion Pro SSC GripLink that came on my Cosmic Pro wheels are remarkably similar to Hutchinson Fusion 5 All Season.

Bulges in tyres do happen. I've had it on Schwalbe Ones
Bubbles are a bad tire..100+ psi is okay..if you have broken cords you get bubbles..Continental and Maxxis are two brands I have used that got broken cords after pot holes and or some lumber I ran over running 85-90 psi..
I am nothing but happy with Mavic wheels..I got some descent mileage out of the ( hospitality) tires that came as original equipment on the bike. Most tires offered on bike builds are medium quality and slightly lighter most often. The big manufacturers get great prices and the bikes offered for sale at the shop have the lightest weight possible, which is a major ritual a road bike buyers..there is something satisfying about lifting up a bicycle and having it feel light..
I use Conti and since the Gator skin was introduced I feel like it's a pretty good compromise..I get good life, performance,feel and decent time between flats.. I use 28's and I have used Gran Prix 4's and I like them also..
when I experimented with low pressure I had bubbling sidewall main problem is "wire" flats were somehow I run over tiny pieces of wire,which I have been told are the metal belt cords from worn out car and truck tires..
I have not really found any tires that are immune to bullhead thorns
Reactions: Sciatic
I am roughly your weight, and have a set of Mavic Ksyrium Elite wheels. They are a few years old and I've ridden thousands of kms on them.
They are the best wheel I've owned. Never ever had an issue like you describe.

I would say your PSI is way too low.

I only use continental tyres, GP4000s on there at the moment. All sorts of different brand tubes.
My psi for any weather is 110.

I think i've only ever had a couple of flats and never a bulge issue. I ride over pretty much all surfaces with them including the occasional cobble, gravel, even sometimes dirt trails (all on my road bike).
Reactions: Cookster15
The mavic tyres I got with my 2016 Ksyriums were not really very hard wearing, particularly the rear which wore through susprisingly quickly. Currently using Schwalbe Ones which have been very good - puncture resistant so far (after circa 3000km in all weathers) and no reason to suspect they aren't working effectively with the rim (that's all marketing guff in my opinion).

Just a really good pair of lightweight, hassle free wheels (still in true after all this time) and tyres that feel fairly supple and fast and don't get punctures - what more do you need?!

The OP is talking about tyres, not wheels, and psi depends on tyre width. 110 is way to high for anything other than 23mm, and even then it is high.
They mentions carbon bike, wheels, tyres, their personal weight and the fact that the tyres are bulging. Because I have pretty much the same setup as the OP, and weight, maybe i'm a bit heavier, I let the OP know what setup I run. I've had no issues.

Yeah, 110 is on the high side, but the heavier you are, the higher PSI you run. Like I said, I've never had an issue at all.
Sep 19, 2021
I've got a blistering/delaminating (?) rear tire - Mavic Ksyrium Elite UST wheel with Yksion Pro 2 UST tire. Running 85 PSI (which is max recommended or thereabouts on the tubeless). I weigh 78 kgs and I've done less than 2000 miles on the tire - it was a new summer bike this season. I love the wheels and the puncture-free ride but a tire that lasts less than a year? Had these wheels on last year on previous bike - tire also lasted less than a season, that time not blistering but instead just wearing overly - no longer a round shape. Not super-keen to go through the rigmarole of finding a non-Mavic tire that fits properly i.e. can get on (and off) without being superman,

Currently looking at going back to inner tubes for next season, with either Fulcrum Racing Zero or DT Swiss 1400 DICUT Oxic, with some regular Conti GP 5000 and tubes. (Academic in a month or two as it'll soon be winter bike time)
Just use the appropriate Continental for your needs. I've flirted with other brands for various reasons but always come back. Can't go wrong. But keep them pumped up. Low pressure is overrated and means much higher rolling résistance and likely pinch flats and possible sidewall damage. We sit on road bikes not sofas.