Koyote

You've gotten some advice in this thread, and I'll be interested to see a report on whether any of it works. Or you could just spend a minute topping off the air pressure in your tires before each ride. That won't hurt anything.

cyccommute 

Find another person using the same tires and you are well on your way to a statistically significant result

All kidding aside, if you have 4 tires that all behave the same way, you have the diffusion rate for your tires. It’s not a bad seal because that would require all 4 tires to have exactly the same problem which is highly unlikely. That’s just how much air your particular tire brand loses in about 24 hours. It’s perhaps a little high but it’s not outside of the range of expected losses. Most of us don’t actually track how much air is lost. We just pump them up before each ride.

teeebone

I top off before each ride - it is no big deal. But I was just trying to find out if my tires not holding at 50 but always holding at 40 was normal....plus the guy at the bike place inferred it was happening because of my weight (which I would have known was wrong if I had taken the pressure after the ride not the next day).

Moe Zhoost

I really think that what you are seeing is an artifact of mounting the pump head on the tire. Assuming that you are adept at attaching the head to the valve without losing air, you have still added volume to the system, i.e. the pump head and tubing back to the check valve in the floor pump. As a consequence, the pressure of the tire/pump system will drop. You will lose some pressure due to diffusion but 10 psi overnight is a stretch.

Try this: Pump up your tires to 50 psi, then unmount the pump head. Remount the pump head and see what pressure you read. I bet it drops some.

teeebone

I did that and it stayed at 50. It is not the artifact of mounting the pump head on the tire. Just got back from another ride and only went down to around 47.....can guarantee you in 24 hours with no riding it will be down to 40. These tires just will not hold anything over 40 for more than 24 hours (even with no riding). When I check again after it gets to 40 they always stayed at 40.

Koyote

Did you try any of the tips I referred to in Post #9 ? Just curious to know if they worked, assuming you tried them.

RiceAWay

There are two kinds of "tubeless" - "tubeless" and "tubeless compatible". Tubeless tires have a heavier soft rubber bead on them that supposedly doesn't need sealant. Don't believe it. Although it does allow you to cleanly remove the tire they are a REAL pain in the butt. They are EXTREMELY difficult to mount on the newer Tubeless rims and i have destroyed 3 carbon aero rims trying to fit these things. Also, do NOT believe that tubeless doesn't get flats. They do, the holes are just bigger and much harder to repair. So after a couple of years of using them I am returning to pure clinchers and tubes. And Aluminum rims with so much better braking. I spent an entire week trying to get a tubeless tire on properly and after breaking the rim using the plastic tire jack designed to pull them on I gave up and bought bought some new Campy clinchers and Continental clincher tires. And taking about five minutes to install both new tires was such a relief I can't even tell you.

Tires do not significantly lose air because of your weight but rather because they sit overnight and lose air through the pores in the rubber that are a part of the material. Tubeless tires are significantly more expensive than clinchers as well. My experiments are over and while tubeless sounds good the air capacity of a bike tire is just too small to allow them to work well.

alcjphil

More often than not I have used road tubeless tires without sealant. My wheels(Campagnolo Shamal 2way fit) seal well enough that they hold air almost as long as butyl inner tubes. I have not used any tools other than my hands to mount tires for many years, in fact they are no more difficult to install than conventional clinchers on the Campagnolo Neutron wheels on my other bike. I am currently using sealant because my current tires(Hutchinson Fusion 5) are a couple of years old and were starting to lose air a bit quicker than when they were new

shelbyfv

I'm quoting this because it didn't seem to catch OP's attention first time around. This is your best explanation for what's happening and advice for what you should do going forward. Over and done.

teeebone

It caught my attention and it makes sense but I am only allowed 5 posts per 24 hours so I cannot respond to all of them. If losing 10 PSI after 24 hours (without even riding) and losing no more after that is normal for these tires so be it.

teeebone

I will but I have my "free checkup" from the place I purchased the bike so I don't want to do it until after they look at my bike....maybe this is something they will do after I tell them what is happening.

Koyote

That's a good plan.

cyccommute 

Pressure loss due to diffusion isn’t linear. You lose more pressure faster at 100 PSI than you do at 40 PSI. 10 PSI loss from 50 to 40PSI in 24 hours is a bit more than I’d expect but you have 4 tires that do the same thing so that’s what your leak rate is.