Tyre Pressures

[Jamz]

There is kind-of a universal standard pressure of road tyres of 36 front and 42 rear.

Now I know this is best not to be messed with unless you know what you're doing (on a road bike), but how do different pressures affect handling?

I know at a very basic level lower pressures will give you more grip, but then there are anomalies like people saying they actually run HIGHER pressures in the wet - to open up the tread more for water dispersal.

Racers seem to run much lower pressures - is that purely for grip or to compensate for heat expansion?

Do any road riders strongly object to the 36/42 'safe' pressures?

[cargo]

I run 31 front and 30 rear

[masterofinsanity]

they seem a bit high Jamz, i thought it was 32 front 34 rear?

[deviant]

you've spent too long on lardy bikes Jamz.

Recommended pressures from Avon for the Viper Sports on my 400 for the road are 33F 36R.

Recommended pressures from the guy that does tyres at No Limits trackdays for a fairly cool day were 32F 31R.

the reason for lowering them on track is to compensate for the higher temperature and hence get a similar running temperature.

[deviant]

I know at a very basic level lower pressures will give you more grip,

Oh and this is wrong. I'd have to fish back through my uni notes to be able to explain it, but in theory a higher tyre pressure gives more grip. In practice this isn't necessarily true - among other things a lower pressure will cause the tyre to warm up quicker, and hence give more grip quicker.

Try driving a car with hardly any air in the tyres, it will slide around all over the place.

[Jamz]

I know at a very basic level lower pressures will give you more grip,

Oh and this is wrong. I'd have to fish back through my uni notes to be able to explain it, but in theory a higher tyre pressure gives more grip. In practice this isn't necessarily true - among other things a lower pressure will cause the tyre to warm up quicker, and hence give more grip quicker.

Try driving a car with hardly any air in the tyres, it will slide around all over the place.

Yes, that's why I just said 'in theory' - too low and it goes to the other extreme, and the same with too high!

It also affects the tyre wear in much the same way.

Something like NASCAR is great to look at for tyre pressures, because there's not a hell of a lot more they can change to gain an advantage, and it can win or lose the race!

[rene]

i run diffrent presures for every bike i've owned, start of with the standard then keep ajusting them untill you find somthing your happy with. Generaly i end up with around 36 rear 32 front.

In whinter i rase the PSI to compensate for the lack of temp. Just have a play, you wont die as soon as you get on the bike if the psi is not standard!

[Jamz]

So what should you do in regards to pressure to affect handling?

For faster turn-in?

For better corner stability?

[rene]

The correct PSI effects everything, strate line stability, trun in, grip ect ect end of the day your tyres are the bigest factor in all of them

[Gemini]

the mobile tyre fitter i used last week must have been well impressed with my knowledge on this subject.

he asked what tyre pressure i ran and i remained silent with a rather blank look on my face!

fook knows i said

gem

[Jamz]

the mobile tyre fitter i used last week must have been well impressed with my knowledge on this subject.

he asked what tyre pressure i ran and i remained silent with a rather blank look on my face!

fook knows i said

gem

LOL I have to admit I've never actually checked my pressures in the 4 months I've had my ZX9R...

Whatever they are works well, though!

I definitely ran 36/42 on my ZXR400.

[Gemini]

i suppose the weight of your bike dictates the tyre pressure then?

i guess that means about 60 in the front and 80 in the back for me then!

similar to a boeing 747

gem

[Xphyral]

air expands when hot so a fast rider on track running a road pressure will find his tyres becoming over inflated and reducing the amount of flex in the tyre along with the slightly smaller contact patch. reducing overallgrip

a fast rider on the road running track pressures will also have problems because generally you cant keep a high enough con_stant speed to keep the warmth and expansion in the tyres. but a fast rider on the road will probably benefit from running slightly lower than the manufacturers reccomendation. lower pressures do increase tyre wear though, so play with em. generally most manufacturers tyre pressures are just fine for everyone on the road.

As for tread in the wet, it only helps to clear water when there is a large amount of water standing on the surface. if it's damp then using a low tread, sporty, soft compound tyre with a fast warm up time will give you better grip than a hard, heavily treaded touring tyre. I fit touring tyres in the winter not for grip, but because a cold sports tyre wears faster than a hot one and riding sporty tyres around in the freezing cold decreases the life of the tyre a lot. I recently had a set of maxxis supermaxx sport fitted, and it's rained that last couple of days but they heat up faster than the continentals i had before and grip much better in the wet than you would think con_sidering the limited tread pattern they have. The times i've ran my summer tyres into the winter months, if i can get em heated up i have just almost as much fun in the winter rain as i do in the summer dry days but it isnt really very good on my wallet to start replacing tyres every 3 months.


maxxis supermaxx sport

I really cant reccommend these tyres enough tbh, i got mine for £180 fitted and oh my god there fantastic.



P.S. Baz you really gotta fix that congratulations emote,

[masterofinsanity]

P.S. Baz you really gotta fix that congratulations emote,

sorted!

[Brett]

I just checked my tyres and they where well low(around 26psi). It was only three weeks ago I put air in them(34/32).
Slow punctures on both tyres, or just normal air loss?

p.s. Gem, where do you get your avatars from, they're the nuts?