Just bought a Topeak digital tyre gauge because I was sick of the random pressures indicated by the track pump gauge [which seems fairly common on all pump gauges]. Got it home and of course went to check the pressures in my bikes’ tyres. I was shocked to find the 29x 2.25 s were at 12psi and the 26×2.25s which I thought were very high because they were new tyres and I had whacked them up to seat and seal, were at 25psi. If the new gauge is reasonably accurate, and I think it is , I have been massively overestimating my tyre pressures which might explain a few things like tyre roll. I had even been pricing wider rims being convinced that too narrow a rim was the problem. So what pressures do people run for normal trail riding in these tyre sizes?

I was sick of the random pressures indicated by the track pump gauge

You need to get more important things to be sick of.

I was shocked

You’re over dramatising.

But to answer your question 30ish. But obviously that could be shockingly inaccurate.

This STW everybody is over dramatic!

78.9%

Maybe your digital tyre pressure gauge is faulty.

Unless you’re working out the tyre pressures to run through applied maths calculations the actual numbers don’t actually matter if they’re working for you. What you really want is repeatability so that when you pump your tyre up before a ride, it rides the same way it did last time you did that.

If you’re getting tyre roll, add some more air irrespective of what number you think you’re running.

26×2.25s which I thought were very high because they were new tyres and I had whacked them up to seat and seal, were at 25psi

Perhaps they aren’t so well sealed?

the answer is ‘not very’.

but that’s ok, don’t worry about that.

most importantly, is it repeatable? do you get the same reading when you remove/fit the gauge a few times?

and is it sensitive? – can you see a small change? – like after you’ve let a bit of air out?

they should be fairly repeatable, and sensitive. That will allow you to find what pressures work for you.

If the new gauge is reasonably accurate, and I think it is

Or it just has better resolution

as a qualified engineer, i have my pressure guage recalibrated weekly.

its accurate to +/- 0.01psi

i my tyres medium soft on 26″ wheels.

Aren’t Ashima rotors pretty well known for this sort of thing?

How accurate are digital tyre gauges?

It costs 25quid so probably not very.

I work (as an Application Engineer) for a company who makes Pressure Measurement equipment and sensors.

I’d be interested to get one of those Topeak gauges and see how accurate it really is. Has to be said they make no claims on accuracy.

I have been toying with the idea of getting a couple of our cheapest digi gauges (they still cost 450quid), a decent HP pump, LP pump and some adaptors for Schraeder and and Presta valves and making up a little test kit.

I wonder what the likes of Mojo and TF Tuned use to measure pressure in forks/shocks…?

for normal trail riding

Does anyone still do that?

I thought it was all Enduro-Core and Shred-Gnarr these days?

Anyway, I checked mine this morning and they were 8.5 psi.

Perfect

How accurate are digital tyre gauges?

is a question akin to “how heavy are bikes?”

My topeak track pump over read by 5 psi.
So I have been running my tyres too low for years.
I go weight in stone x2 +2psi for the rear & -2 psi for the front for my dh & enduro bike.
I also worry incessantly whether my suspension settings are optimal. Fortunately this is the only thing in life I have to worry about.

Aren’t Ashima rotors pretty well known for this sort of thing?

😆 that’s the other thread!

I have the same Topeak gauge and thought that it read quite low. I also have a Sealey gauge for the car and tried that and it was the same pressure. I then tried my Topeak track pump and the pressure was 5psi greater than the gauges, then I tried my 9.99 pump and it was 15psi greater than the gauges.

As someone else says it really doesn’t matter what number it reads, as long as it is consistent and it is.