[Closed] I've been doing tyre pressures all wrong

Lo and behold my bike tyres, being at an indicated 25psi on the track pump, were at 36 psi on the 4 different monitors I tried in the shop...

A whole new world awaits!

I always knew there was a conspiracy afoot 😐

I gave up and just go by the pump and feel...adjust to terrain method.

The dial on my track pump rotates, not sure it's deliberate but it's amusing. Maybe yours can also rotate and you may be able to calibrate it this way!

I did my tyres at Tesco forecourt to 36 psi (car) and then felt like car was even more skittish in the strong winds last week, only to then go home and use old school pencil gauge which had them all at a uniform 43psi!

It worked the other way round for me. Its when I got a proper gauge that I found out I was running my bike tyres at 15/17 psi front/back 😯

My £90 Lezyne track pump under-reads by 10psi compared to my Topeak pressure gauge.

Given the WC mechanics use the Topeak gauge I use that as my constant

My selection of pumps can vary pretty wildly. Like a lot of things with measurement, seems some calibration is required and repeatability is the critical thing. I've learned 20 is actually 17 on the one I use most, and a pocket digital gauge is a decent way of getting that repeatability with different pumps.

You need a calibrated thumb 🙂

I guess, ultimately, consistency is key really...

sqidge test is the only way.

my bontrager charger pump only reads 20psi-40psi i darent go higher than 40psi as the tyre is practically humming.

Recently got a digital gauge as my track pump seemed to be getting a little optimistic in its old age. It's certainly taken the guesswork out of tyre pressures and will also prove useful for the car too.

Accurate analogue gauges are expensive.

Garage airlines fall in much the same category, they shouldn't be expected to be accurate.

For most people, picking a single instance and using that as your standard is fine, just understand that 'the same' reading on another pump probably isn't.

Same applies to things like torque wrenches. Anything not maintained and recertified regularly is a guide only, but for most people that's fine as you're usually within design tolerances of whatever you're wrenching up ...

It's when you get to the extremes of range things start to go really wrong!

As long as you're selecting the pressure based on feel/experience (how low you can go before pinching tyres all the time) then does it matter if there's an offset on your gauge reading?

my new wheels are 30mm internal. tyre pressure read at 10 psi rear and underscale on the front!

This is on an MTB specific track pump. Going to invest in a gauge.

Yeah, I keep meaning to invest in a digital gauge. Thing is though, if you are only comparing one gauge to another, how do you know which one is accurate?

You really need a few mates who all have gauges to do a comparison....

Always been a bit wary about using a digital gauge on a tyre with sealant...It's not like you can give the handle a quick pump to get rid of any fluid...

The old rule of thumb, before thumbs became accurate digital measuring tools, was pump up your tyres until the deflection was about 15-20% with your weight on the bike.

Works on all sizes of tyres IMO.

Or direct download of xls file that works with Google Sheets...

Plug in a few details, any tyres including fatbike.

Bit of an eye opener for me, what is said I should use for my 38c Marathon Cross, with me being ~82Kg all kitted up to ride and the Wazoo being ~12Kg in skinny wheel mode. Guessed 40% weight over front wheel with 35mm stem.
I'm now using ~60/70PSI, way above suggested, but min. suggested pressure on tyre wall is 50PSI.

BoardinBob - Member

Given the WC mechanics use the Topeak gauge I use that as my constant

I have 2 of those topeak gauges, they read differently 😆 But accuracy's not that important really, who cares what psi they actually have? Only thing that matters is consistency

We have a digital SKS Airchecker and a digital Leyzine pressure overdrive that both read the same, two other track pumps that read quite a bit higher.

I couldnt tell you what my tyres have in them pressure wise. I ran them softer but it felt squirmy on the rear and i got a couple of dings in the rim. Increased it until they felt good to me and run a little less in the front.

Feel is much more important than what pressure is actually in them

That spreadsheet calculator is interesting, but throws up some odd numbers for MTB.

Suggested 25psi front and 38psi rear for me!

According to my (based on this thread pretty inaccurate) track pump gauge I'm currently running 27 rear and 25 front...

I tend to use the apple / orange / banana approach. Currently riding on oranges (apples for rocky trails and bananas if something's gone wrong).

nairnster - Member

Feel is much more important than what pressure is actually in them

Yeah, but once you have the feel you want, and you know the pressure, you can replicate it reliably. I couldn't care less what pressure I like, but I want to be able to get it back after a flat.

Hi. My track pump was showing 30psi but was actually only 20psi. Didn't really help my rims. Got a Rolson pressure gauge pretty accurate , checked in shop against expensive pumps with gauges and it's accurate. Only costs £9-£10 . Last one lasted just over a year . So can't complain.

Yeah, but once you have the feel you want, and you know the pressure, you can replicate it reliably. I couldn't care less what pressure I like, but I want to be able to get it back after a flat.

True, but unless you initially pump them up with the same pump you carry on the trail, as this thread proves, the pressure is unlikely to be the same even if the guage claims it is.

Garage airlines fall in much the same category, they shouldn't be expected to be accurate.

Depends on who's in charge though. When I had a petrol station years ago, Weights & Measures (now consumer protection) would come out every so often to check the pumps for accuracy. I always got them to check the airgauge as well. It was rarely 1-3 psi out over a range from 25/40 psi.
I've got 2 analogue gauges & a track pump, they all read different.