[Closed] Tyre pressures???

Way too many variables. However, I'm a big lad and normally well below the minimum on the side of the tyre.

there is a forumla on the stans website that works on your weight in lbs, divided by seven.

then -1 up front and +1 at the rear (iirc)

that would put me in the low twenties. i always put tyres at 30psi, bikes cars anything really.

I noticed this too recently while sticking new tires on, never bothered about minimum pressure. 14 stone, run well under advised pressure but am tubeless. Just go with what feels right and touch wood (head) no problems so far.

Im big and heavy and always pump my tyres to 40 + as I dont want to waste time fixing pinch flats

The tyre manufacturers have to cover their backs by putting a minimum pressure on the tyre. I am 17 stone plus and ride with 30psi in the front and 35 psi rear on 2.2 Conti Rubber Queens, any lower on the front and the tyre starts to roll off when pushed in bends any lower on the rear and I suffer from the tyre burping air out.
Pressures are like tyres in general a case of test what works for you and run them how you want them. If you were having no issues before with the low pressures go back to them!

Yeah, I think around the 20s suits me. Otherwise going over wet rocks is a bit too hairy!!

I like around 25-30 depending on how grippy the trails are at the time. Tyre size makes a difference too - in bigger tyres the same PSI feels harder (unless I'm imagining it).

(IMO)It's worth messing about with pressures to see what suits you best. I found this can make a huge difference, and will change from brand to brand.

35-40 for me or I get too many pinch flats.

The Stans recommendation is (weight in pounds / 7) - 1 for the front, (weight / 7) + 2 for the rear. However, being British it's much easier to do (weight in stone x 2) - 1 for the front, (weight x 2) + 2 for the rear. It's a good starting point for typical tyres. The larger the tyre volume and the heavier/stiffer the carcass, the lower you can go. With large but light carcass tyres I've found the ideal pressure range can be quite narrow - too low and they squirm, too high and they boing. The recommended pressures on the sidewall are best ignored.

Anything less than 35 on my 2.4's and it's pinch flats all the way down. Maybe I ride dead fast, maybe I'm too fat or maybe it's both 😀

well.. stans recommendation gives me 18.8 front and 20.8 psi rear.. so maybe not. maybe it's for fat americans. now that i have a new track pump i know i run in the high 20s. i do it by feel (both the tyre and the ride) though.
obviously bigger tyres will want lower pressures right? though i'm too tired to explain why right now :/

I like around 25-30 depending on how grippy the trails are at the time. Tyre size makes a difference too - in bigger tyres the same PSI feels harder (unless I'm imagining it).

You're not imagining it.

Force = Pressure x Area

So if you take the pressure as a constant, but use a bigger tyre, a larger force will be required to make it squish as much as a smaller one. Hence why if you use narrow tyres, you need to pump them up harder! Or also why fat people need to use more air pressure for a given tyre than thin people... Science innit! 😉

FWIW, even though I run tubeless, I'm closer to the GW school of thought on tyre pressures than the Stans one. I'm about 11 1/2 stone, but run 35psi in my 2.25" back tyre, and about 32psi in my 2.2" front. Main reasons is any softer and I'd either ding the rim regularly, or risk burping. Some people will get away with a lot less, but it depends on your riding style, so if you're really smooth, you could probably drop 10psi out of the tyres over what I run even if you're the same weight as me.

FWIW, Stans recommends 22psi up front and 25psi out back for me... Exactly 10psi lower than I run. I'd have to be running 2.5" Maxxis dual ply tyres to contemplate that low pressure I reckon, otherwise I'd just ding my rims constantly.

14 and a bit stone - 28 in 2.5" Dh tyres around 35 in anything skinnier. A good guide to me is you should just about be able to see the tyre deform under your weight, and deform just a little bit more if you shift your weight onto that wheel.

I just pump them up, until they feel the right "squidginess" (very technical term...).

Honestly have no idea - between 25-35 perhaps?

i use a bit sqishy on the front and rock hard on the back.

All this lovely pseudo-science, and then we measure the pressure on an uncalibrated gauge.....

I have gauges that are over 15psi wrong at 30psi, so check it against something known, such as a petrol forecourt gauge before chasing the errors.

PaulD

er, i think if you would like to check the paperwork that i have had my right thumb and forefinger calibrated just last week

2.3's run at 25-30 psi for me, a 14 stoner. Any harder and the amount of grip seems to suffer really badly. Very rarely get flats.

95kg rider and 40psi front and back.
Yes, I know it's wrong, but I run my fork with no sag as well and it works for me.

jedi do you really run a huge difference front and rear?
been tempted to do that but always thought i "shouldn't" for some reason..

Tony, very interested in the thinking behind that as well.

PaulD, Ive got three gauges all within 1psi of each other. As I only want a relative measure so I can go higher or lower next time, am I allowed to use my psi readings?

Front always softer than the back. Quite often run the back quite a bit firmer as I like a bit of drift 🙂

DH 25-40

xc 30-40

All depends on the conditions. The better i've got a riding, the higher pressures I can get away with running.

I run 35 ish depending - any softer and the tyre squirms around - a feeling I hate

[quote=jedi ]i use a bit sqishy on the front and rock hard on the back.

Aye, that's the method I use too, works for me.

I pump em up until they go pop (50-60psi).
Then let them down using the thumb technique for pressure. 😉
Last time I checked it was 25 on the front and I couldn't really care about the rear, it spends most of the time bouncing around, but its definately harder than the front.

O,

I am pleased your gauges are consistent. At least you do not have to look at the reading and calculate what it really means and then work out what you want in that tyre on that day.
I do run different pressures in different tyres and find the whole issue a pain, particularly as I ride 10 miles each way to Swinley and prefer much higher pressures on tarmac for lower drag...wimp I know.

The real point I was making is that it is fine to work out what pressure you need (scientifically or from personal experience) but to just assume your gauge is accurate can be an assumption far to far.

Happy trails....unfortunately muddy ones down here at present.

PaulD

So does everyone ignore manufacturers recommendations in other areas, say running their car tyres at 15-20 psi?

I just pump them up fairly firm and then make the front one a little softer. Only used the pressure gauge once when I recently tried 30psi. Thought they squirmed a bit, but could have just been the single ply sidewalls. But it depends on the tyre size, tread, side wall strength, tubed/tubeless, tackiness and terrain. If it's rocky/rooty then I'll run them really hard to avoid pinch flats.

I think a lot of people are way to anal about their tyre pressures, hence the hundreds of posts on forums about it (not just this forum).

Tom KP

So does everyone ignore manufacturers recommendations in other areas, say running their car tyres at 15-20 psi?

i use a bit sqishy on the front and rock hard on the back.

Wish I could run 30 on back of FSer, oodles of climbing grip but as soon as I head downhill it's a recipe for (puncture) disaster

but to just assume your gauge is accurate can be an assumption far to far

pump up to X pressure ride, adjust to Y pressure ride, repeat, when you get the pressure that works for you on your bike on your trails remember it.

yep i run 35-40 psi on my tyres, slightly less on the rear wheel..

30 front 35 rear summer , 25 - 28 winter 15 stone rider 2.25 Maxxis running tubless on Stans Rims