Inflating 20x4 fat tires - can I go a little further on the pressure?

[FrankR]

My bike has 20x4 tires. They are supposed to be inflated to 20PSI, which is what I have them at. I read constantly of people getting flats on these tires because they are set up to be part of the suspension, so to speak. Can I go up a bit more in PSI safely to make them a bit firmer and possibly stronger?

 

[Mr. Coffee]

Slightly over inflating the tire is probably okay, there is typically a lot of slop in the tolerances and you are unlikely to kill yourself if you inflate the tire to 25psi or so.

However, doing so will have no impact on preventing flats or making the tires or wheels stronger.

There are lots of ways to minimize flats and you ought to look into those options if that is a concern.

 

[FrankR]

Thank you. I am aware of some of the other options - flat out, liners, etc. - and I will definitely go down that road when I can. As a new rider, I'm just immediately concerned about a flat because it will bring this journey to a stop. I am not equipped at this time to change one of these flats.

 

[Gordon71]

Check the tire. They should say what the max psi is. On the 26X4 tires on my Rad Rover they say a max of 30psi. Manual recommends 20 but you can either drop them down to around 5 or up to 30.

 

[Tars Tarkas]

Thank you. I am aware of some of the other options - flat out, liners, etc. - and I will definitely go down that road when I can. As a new rider, I'm just immediately concerned about a flat because it will bring this journey to a stop. I am not equipped at this time to change one of these flats.

Why in the world not?! There is absolutely nothing (reasonable) that will prevent flats. Carrying a flat kit, including the necessary tools, air, and probably, a spare tube, are minimal requirements for riding much beyond your front yard, in my opinion, at least.

 

[m@Robertson]

First of all, NO you cannot exceed the recommended max pressure on a fat tire. On general principles with bicycles, the max pressure is as far as you want to go, and you can go a little more. But on fat tires even though the pressure is a 'low' 20 psi, the surface area of the tire is so large, the pressure from the tube underneath can rip the tire casing apart. As a moderator on a FB user group with thousands of fat bike riders I have probably seen this happen 50+ times.

Besides, 20 psi on a fat tire makes it a rolling rock in terms of comfort. The only time I do full psi on fat tires is when I am using them on a cargo bike and that bike is going to be carrying a couple hundred pounds (literally) of groceries.

Lastly, inflating a tire to its max will do nothing to safeguard you from getting a flat. In fact its sort of the opposite. Consider this: Just put a tiny puff of air into a balloon. Poke it gently with a pin. You can poke it a bunch of times without issue. Now blow the balloon up. Gently graze it with that pin. BOOM. This is why I use oversized tubes everywhere I can. A tube under hi pressure and distended is much easier to breach with a thorn or similar.

What you DO get is sidewall strength (just like with cars... same principle). Thats great for load capacity and thats why I do it for cargo loads... but it gives no benefit for flat-proofing.

Get yourself some FlatOut. Its the premiere product for fat tires at lower pressures and it will solve almost any problem before it becomes one.

(e?)Bike Flat Prevention

As a daily rider for decades, I have some thoughts on this subject. Mostly along the lines of “no flats allowed, ever”.

talesontwowheels.com

 

[FrankR]

Why in the world not?! There is absolutely nothing (reasonable) that will prevent flats. Carrying a flat kit, including the necessary tools, air, and probably, a spare tube, are minimal requirements for riding much beyond your front yard, in my opinion, at least.

You are right. The first video I watched for my bike had someone do an awful lot of disassembly to get the tire off.
Watched others, and it looks like not much more then the main nuts and then a hex nut on each side.
That, plus the tire lever I have on order, and the fresh tubes I already purchased, and - I will do it. No way I'm idling because of this.
Enjoying this too much, and, the exercise, for me personally, is significant and very important.

I'm always a little timid about such stuff. I'm not the most "handy" person. But, it is becoming obvious I need to learn and take responsibility for the maintenance.
Building up a tool box.

 

[m@Robertson]

You are right. The first video I watched for my bike had someone do an awful lot of disassembly to get the tire off.
Watched others, and it looks like not much more then the main nuts and then a hex nut on each side.

Its a lot less than that! Lookit this pic taken from that article on flat prevention I linked above. Notice anything about the wheel?

Its still on the bike! No wrenches. No disassembly. I had the bike up on a stand in this pic, but I have also had it laying down on the grass (or dirt if I am unlucky) on the side of the road.

There is no need to remove the wheel.

Just get the tire off the bead and pull the tube out just like I am doing in this pic. From there you have to find the hole. Hopefully you have an idea of where to look from pulling whatever it was out of the tire. But if you do not, then inflate the tire some and find it either visually or do this: Run your ear close to the tube as you work your way around it. It WILL require some effort to deal with the fact that the tire is still on the bike frame, but you can do it... especially on a fat bike. If you can hear the hiss but not find it, then when you get close ... put your lips close to the tube and that sensitive part of your body will feel the slightest escape of air where other body parts may fail you.

Obviously you want as few witnesses to this as possible. But as a daily rider who rode fat bikes for years commuting, not to mention many others back in the bad old days before sealants like FlatOut were on the market and mostly saved my ass from having to sit on the ground and go thru this... the lips are the way to go if you are stuck and can't find the hole.

edit: Oh and also get yourself one of these! In 2022 only suckers carry hand pumps unless they are backups. Especially fat bike riders.

A Lightweight Electric Emergency Bike Pump

Got an ebike? Use the big battery you are already lugging around to power a small portable pump.

talesontwowheels.com