Tyre pressure for diff riding types

[MikeyP]

I ride it all, but don't know a thing about tyre pressure.
Someone once told me the less pressure the better, so I ride IRC Kujo DH with super thick tubes. I keep the pressure at about 8-15 psi and have never had any trouble with pinch flats. I ride DH, urban, jump, skatepark, and really like hucking drops. (full susp bike)

I only began wondering about pressure when I noticed skatepark riders (with proper urban tyres) ride with tons of pressure. I'm too lazy to be changing tyres all the time & too poor to have more than one bike...

So, would I be riding any of these basic areas better with more pressure, or is super-flat the best for all on my chosen tyres?

[Ryan]

8-15psi is crazy low for any conditions...I run about 60psi in my tyres for skateparks / street / jumping and about 20-30psi for DH riding depending on the conditions (closer to 20 unless the track is super rocky).

With the range of soft compound tyres available these days (unfortunately your IRC's arent one of them) crazy-low pressures aren't really that necessary.

[MikeyP]

I was told 8-15 was good for grip in urban trials-style riding. Also that since tyres are the first point of contact, low pressure is best for hucking. Were they all stupid? Are there any dangers to the pressure I'm running on big hucks? What's the lowest you'd recommend?

Last question - the ads for tubeless always say 'so you can run lower pressure' - why lower pressure?

[mike&nat]

running that low pressure for big hucks is bad because you will hit your rims when you land and brake them

[ajay]

Were they all stupid?

Yes.

i run about 20-25psi on dh (depends on the track)
Jumps about 30 ish (again depends on the soil etc)
Street - i dont ride much street, but about 40-60 (depends how tired my arm gets from pumping up the tire..)

But yeah, 8-15 is STUPIDLY LOW! sometimes lower pressure can give more grip, but not 8psi... more like 18-19 (absolute lowest imo)

too low pressure can result in loss of control of your bike, busted rims, etc...

[Tomas]

You dont have troubly with rolling the tyre off the rim that low? Far out. Cornering quickly with 12psi in my tires and it rolls off my 321.

[fat_tyre_nick]

I ride evrything with my tyre pressure on about 30-35 psi riding on my haro hardtail.

[MikeyP]

You dont have troubly with rolling the tyre off the rim that low? Far out. Cornering quickly with 12psi in my tires and it rolls off my 321.

no, no probs at all - but based on what everyone's sayin so far, I'm uppin the pressure! They're 2.35 rear and 2.65 front and stinkin hard to get on - the bead is real sticky, and I'm guessin the sponge in the sidewalls helps with surviving so far running such low pressure.

Still - anyone know why the tubless companies use lower pressure as a selling feature? There's gotta be some advantage to lower pressure for some riding styles - and what styles - only xc?

[MUGEN]

Running tubeless is benificial to XC only because of the lower rotational weight. I cant think of anything else really because at the pressures XC racers run, pinch-flatting rarely happens.

I myself run around ~20 at the back and ~15 up front. Dual ply maxxis tyres refuse to pinch flat. :p

[the F.H.B]

to a point running lower pressures can increase traction and comfort but if you run to little pressure the tyre will deform during cornering, causing it to wash out.
when tyre companies go on about the benifits of tubeless tyres they genrally talk about the fact that you cant pinch flat when running lower pressures (in downhill and freeride), and lower rotational mass (in cross country and enduro)
gotta ask how long you've been using such low tyre pressure? have you ever had rim damage? id be amazed if you havent...

[Rexy]

For general all around riding id say 25-30 is bang on the money.
Chuck it down to 20 maybe for downhill, for urban 50 is about on the money.
Basically with the higher pressures for urban it helps you to roll faster, and it is also very annoying when the tyres "squidge" down when you are doing more techy stuff.

[MikeyP]

Rexy - thanks, that's exactly what I was lookin for

The F.H.B - I've been runnin'm this low for 'bout 2 years and never had any rim damage, but that's not the whole truth. I don't have the skills to ollie up onto sharp concrete edges and while I love riding over big sharp rocks, I take it slow. When I'm hucking big, it's always onto a good tranny, and hucking to flat only when small enough to land it easy -big hucks to flat is stupid unless your Ryan Leech or the like. My skate park riding is still beginner (will it ever change?) so as of yet no hard edge landings there either. The only danger I'll have on rim damage is if I start racing downhill - which I'm thinking of doing, and part of the reason for this thread. I wanna get it right before I pour on the speed....thanks for the explanation on tubeless - this helps.

[punkfreq]

i would like to say i use $8 tubes and if i hav them any lower than 50 they pinch doin anythin bigger than rolling off a gutter....it probably doesnt help that im a dodgy rider too....

[MikeyP]

I had "downhill" tubes that I was pinch-flatting regularly til some guys told me about the 'real' downhill tubes available. I was mostly flatting riding urban - going up & down stairwells & hopping up onto ledges (with no style whatsoever). The tubes I ride are basically small motorbike tubes, and you'd pretty much bust a rim before you'd pinch these fattys flat. I know the sponge-lined IRC tyres I'm riding help heaps, but you should really look into fat tubes - they add a ton of weight & are hard to work with, but totally worth it. Any good bike shop would know what you want if you describe it.

If you are flatting big fat tubes - then you better check your rims, rim strips, and how you put on your tyres. It's real easy to miss a caught tube - use baby powder or any chalk-like powder to help the tube straighen out after stuffing it in and triple check for tube/bead/rim contact.

[Mitchy_Bris]

Yeh lately i hate been getting problems with my tyres, The look to be getting slashed on the outside very frequently..and the only possible cause for this would be sharp rocks...but where i ride the rocks are relatively rounded..Has this ahppened to anyone else before?

[Chalkie]

Mitchy_Bris Cant say its happened to me but it happend to a friend a few times, he bought some of the maxxis downhill tubes, ran his tire at 40psi and he hasnt had the same problems since. What tubes are u using at the moment??

[Mitchy_Bris]

At the moment the tubes Im using are specialized roll-x high grade XC tyres..I think i need to opt for a thicker tyre..i dunno. Ill be getting a new bike soon so it should be right..Its just very annoying

[fat_tyre_nick]

yere as mickeyp said, i also have IRC DH tubes because i had regular punctures and i havent had any hard hits or punctures ever since and they maintain there pressure really well and they were cheap $12 each.lol and like mitchy_bris said i also had specialized roll-x tyres and didnt have much of a problem just the occasional flat because of crappy tubes.

[bowzaa]

yeah i ride 1 bike for all disiplines and i just run one pressure:p
i normally have them at about 60psi for DJ's and Urban but find that after riding dh i end up with like 35 psi but maybe that is because i have sh#t tubes :p

[and1]

i would like to say i use $8 tubes and if i hav them any lower than 50 they pinch doin anythin bigger than rolling off a gutter....it probably doesnt help that im a dodgy rider too....

Yes but your a hack rider on a sasquatch thus no one will really listen to you.

[iUDEX_nCr]

wow, such low pressure... i ran about 18psi when i raced xc... but mind you i weigh'd in at about 57kg on race day... too damn lazy to train... plus i came second last in my final race, LOL.

but such low pressure! i know some trials riders run ultra-low pressure, perhaps that's why you were told to run your tyres at 15 ish psi.

it might be more comfortable, but you're rolling resistance increases, and cornering can be a bit of a problem. The bigger bag of air will mean you can get away with it... how's your rim looking?

as far as pressures go, I weigh around 58kg, and ride a norco rampage, w/ 2.5inch folding bead tyres (rated at 20-50psi) with maxxis dh tubes.
plus minus 1psi... omg this is gonna sound so wanky... but i guess use it as a comparative thing...

urban/concrete: front 38psi, rear 33psi
skatepark/jump: front 40psi, rear 38psi
off-road am/fr/xc: front 36psi, rear 34psi
commutting: front 50psi, rear 45psi....

a mate of mine who's roughly 80kg's would be riding the front about 5psi higher, the rear is kinda weird... depending on the terrain but always lower than front, except for commutting... commutting is kinda different, some people like a little plusher...

not everyone will agree, but this is what works for me from experience, but heck I'm learning too ;)

cheers
i

[Mitchy_Bris]

Yeh i usually have my psi on about 50 to minimize the chance of getting a pinch flat, i suppose it depends on where you are riding, I ride DH on shale and crap like that which slices the tyres good and I get regular punctures...which also could be a result of the high psi..i dunno you cant really go wrong with 40psi i reckon..for anything 40 should get you through

[FuTAnT]

Still - anyone know why the tubless companies use lowerpressure as a selling feature? There's gotta be some advantage to lowerpressure for some riding styles - and what styles - only xc?

With the tubeless you're not going to pinch flat, so you can run lowerpressures. In some instances, one would like to run a lower pressurebut you know you might end up pinch flatting, so you have to leave itrunning at a higher pressure. With a tubeless, the idea is you can runthe lower pressures but you won't pinch flat. Just gives you moreflexibility *IF* you want to run lower pressures, that's all.

[MikeyP]

With the tubeless you're not going to pinch flat, so you can run lowerpressures. In some instances, one would like to run a lower pressurebut you know you might end up pinch flatting, so you have to leave itrunning at a higher pressure. With a tubeless, the idea is you can runthe lower pressures but you won't pinch flat. Just gives you moreflexibility *IF* you want to run lower pressures, that's all.


Yeah man, I know 'bout pinch flating - it isn't an issue for me as described earlier in this thread. Some have said rotational weight is tubeless' big advantage, and a small nod goes to better grip - but this is all for XC. I'm wanting to know (and it's been mostly answered) where else you'd run low pressure, why, and especially how low.

[FuTAnT]

urban/concrete: front 38psi, rear 33psi
skatepark/jump: front 40psi, rear 38psi
off-road am/fr/xc: front 36psi, rear 34psi
commutting: front 50psi, rear 45psi....

i

Yeah, wow, that is weird. I always run my front pressures lower than my rear pressures at there is usually less weight bias on the front. The rear tends to cop a bit more a hiding than the front, hence my higher pressures in the rear.

[iUDEX_nCr]

Yeah, wow, that is weird. I always run my front pressures lower than my rear pressures at there is usually less weight bias on the front. The rear tends to cop a bit more a hiding than the front, hence my higher pressures in the rear.

well from an efficiency perspective a higher pressure relative to weight bias is good... as in more weight equals flatter rubber which means more contact with surface i.e. more rolling resistance... so harder rubber equated to less rubber on surface...

I run a higher pressure on the front because
1- less weight, so not so harsh and won't bounce so much...
2- forks take the hits, so no need for softer rubber

the less pressure on the rear, because more weight, so more rough on the rear... if it was hard it'll bounce more...

hmm, but you got me thinking... less force on front, means less tyre displacement... so if you run it at lower pressure you'll have more traction right? hmm... so weird... what do others think about pressure in front vs rear?

cheers
i

[MikeyP]

definitely more pressure rear less front - how much for each riding style is what I'm learning here.

Something else to consider is tyre size as well - always same size or fatter on front - and fatter always has lower recommended pressure rating....hmmm.

Another thing to consider is when & how force is applied front to rear. Think of the development of suspension. There are no rear-only suspended bikes, but plenty of hardtails with huge forks up front. The rear takes a regular pounding over all riding, especially huge forces when climbing. But when hucking & jumping - when downhill racing over drops and rocks - the front takes the strongest impacts even if they are momentary. Hense, bigger tyres up front - running lower pressure to help absorb the initial impact.

When you land with forward momentum, back to front or both at the same time, the front of the bike ultimately takes the greater force......someone correct me if my physics are messed.

Let's not forget braking forces as well - front being the greater by heaps.

I suppose this kind of negates what futant was saying about more pressure in the rear cause it takes a greater beating - I'd say less pressure up front because it takes a greater beating.....and agree with futant as well....more pressure rear because of the kind of forces applied less front and fatter tyre because of the kind of impacts it takes.

[FuTAnT]

I just go with the weight bias. Basically the front has less weight on it, and tends to get less of a battering than the rear. The rear cops most of the weight and the brunt of impacts. By running less pressure in the front I'm eqalising the feel of the rubber and the contact patch.

Experiment with pressures, but I'm pretty sure you'll find it better with less in the front than in the rear, and it doesn't need to be my much, just a few psi say.

[iUDEX_nCr]

so the bigger the forces (i.e. the bigger the hits), the more pressure?

[MikeyP]

no - I would not agree with that assessment

If that be true, bender should be running around 80-100 psi....

rear takes a more continuous and steady pounding, but I do not agree that the rear takes the "biggest" hits, requiring more pressure. See my last post - I believe the front takes the greatest 'hit' and braking forces and the rear the greatest continual small bump and climbing torque.

As such, greater pressure in rear than front - but not more pressure for bigger hits. The big hit riders would want to have their tyres be a part of the shock absorption along with their suspension. Tyres are the first point of contact. According to people in this thread, the pressure has a lower limit, but it would not be recommended to put 80 psi front and rear cause your doin 30 foot hucks.

[punkfreq]

Yes but your a hack rider on a sasquatch thus no one will really listen to you.

and i clearly pointed that out wangmunch

[Jambo]

38 PSI in the front and 45psi in the back serves my purpose..