Tubeless Tyre pressures Query- Tyres say not to go below 30psi?

DanWhyte629

Hello all, i'd be grateful for some guidance. I'm about to go tubeless on my MTB but I noticed the other evening that my tyres state not to inflate below 30psi. Is this warning only relevant when running inner tubes? I thought one of the benefits of going tubeless meant you could run lower tyre pressures (circa low 20s psi) for increased grip?

Am I over thinking this? Yes, i am new to MTBing!

billycool

You are quite right that tubeless set-ups are designed to allow you to run lower tyre pressures. How low you go is up to you and the parameters of grip, tyre roll/burping etc.

Are you tyre tubeless ready/specific? If they are not, that might be why they say 30psi.

What tyres are they?
Do you have tubeless ready rims?

DanWhyte629

Hi billycool, thanks for the reply. That would actually make sense but according to the spec sheet the tyres and rims are:

Rims - WTB ST i27 TCS System, pinned joint, tubeless ready
Tyres -
(Front) Maxxis High Roller II TR 29x2.3 60TPI, EXO Extra Sidewall Protection, 3C Maxx Terra.
(Rear) Maxxis Forekaster TR 29x2.35 60TPI, EXO Extra Sidewall Protection, Dual Compound.

Lots to type there, but the tubeless ready on the rims and 'TR' designation on the tyres , I assume, mean i'm good to go.

Perhaps the warning on the tyre is Maxxis's way of offloading the liability should something happen at low pressures?

david7m

They will be fine, the 30psi is covering their own bottoms.

DanWhyte629

Thanks Chaps, figured I was overthinking this!

billycool

DanWhyte629 said:

Hi billycool, thanks for the reply. That would actually make sense but according to the spec sheet the tyres and rims are:

Rims - WTB ST i27 TCS System, pinned joint, tubeless ready
Tyres -
(Front) Maxxis High Roller II TR 29x2.3 60TPI, EXO Extra Sidewall Protection, 3C Maxx Terra.
(Rear) Maxxis Forekaster TR 29x2.35 60TPI, EXO Extra Sidewall Protection, Dual Compound.

Lots to type there, but the tubeless ready on the rims and 'TR' designation on the tyres , I assume, mean i'm good to go.

Perhaps the warning on the tyre is Maxxis's way of offloading the liability should something happen at low pressures?

Yeah - all looks good to me. You'll just need to check that there is tubeless rim tape fitted to the rims as `tubeless ready` doesn't always mean they are set up for it.

What pressures you run at is a very personal thing. I run mine nearer 30psi as I ride a lot of hardpack and roads in the winter and my tyres roll/squirm too much at lower pressures (it's like having a puncture). Other folk go as low as 15psi as it suits them better. All rim/wheel combos behave differently.

Assume you have everything you need to set it all up?

DanWhyte629

Cheers Billy, I think so.

I've got my tubeless valve kit and tubeless repair kit arriving today but still need to buy my rim tape and sealant. I've been advised to go with 28mm tape to fit my 27mm inner rim width - does that sound about right?

billycool

I'm not sure about tape size to be fair. I'm sure everyone will have an opinion on that!

I'd expect to go for a bit wider than 28mm tape for 27mm rim but I'm no expert.

https://www.huntbikewheels.com/products/hunt-blackshield-tubeless-rim-tape

Some people say the same size as the rim, some say allow 1-2mm either side.

Lots of info on Google if you want to have a search.

DanWhyte629

Hmm, i'll think about the tape a bit more then. That link suggests going a fair bit wider. I've read conflicting advice online so contacted Muc Off to ask for their guidance as I was looking at their tape, and the advice was the 28mm width would be a prefect match.

I'll continue to look at that choice.........

steve_sordy

I use 25mm Gorilla tape from pretty much any DIY store. I get the black with the woven finish that looks like its carbon fibre! I know that nobody will see it, but I like the look of it. If the rim is wider than 25mm, then I put one stripe to the left and one to the right. That ensures there are at least two layers over the spoke holes.

My track record with originally fitted rim tape is poor. Even on new bikes and/or wheels, I have had failures. Not out and out failures that are obvious from the start, but just bad enough that I persisted in trying to get a seal for long enough to get really frustrated. Now I just strip off the rim tape, no matter how good it looks and replace with Gorilla tape. Never had a failure yet. You need to get lots of air in fast. Lots of vids on YouTube.

As for your tyre pressure question: The lowest pressure will be based upon the tyre rolling off the rim under hard cornering with an "average weight" rider on "average trails". In other words do what works for you. The guys that get away with 15psi may be on 2.8" wide tyres and weigh 10 stone in full kit. In my riding gear I weigh 14.5 stone (92kg) and I ride 17F/20R on 29x2.5" tubeless tyres. I used to ride with 22F/24R on 27.5x2.2" tubeless. It also matters what internal rim width and how roubsut the tyres are. So what I recommend that you do is to go out with 30psi rear and 27psi front and see how it feels. If you can feel every pebble and root, drop the tyre pressure 2psi and see how it feels. The try a few fast corners and see how it feels. If it feels a bit floaty or you can see the tyre rippling, or the tyre burps some sealant, than add a couple of psi. You will soon get the hang of it.

All anyone can do is to advise how to establish your tyre pressure, they cannot give you a figure, especially if they aren't riding with you! The Pink Bike video attached is very good. Read the words, watch the video.Outstanding!

https://www.pinkbike.com/news/Tech-Tuesday-tire-pressure-2011.html

DanWhyte629

Thanks for taking the time to post that Steve. I've ordered the last ingredients for me to go tubeless so may give it a go this weekend if i can fit it in!