Tyre pressure - higher on the rear or higher on the front?

[xwhatsit]

So, just to be sure, are you saying that increased pressures will generally extend tyre life?

Well they don't seem to square off so quickly.

I think rear-weight bias has a lot to do with it -- you'll notice most bikes tell you to bump up the rear tyre pressure when carrying a pillion, for instance.

[YellowDog]

Do you run higher pressure in the rear or the front tyre?
Why?

Twisties = Lower Pressure
Straightline Drag = Higher Pressure

[Crasherfromwayback]

Twisties = Lower Pressure
Straightline Drag = Higher Pressure

High speed runs in a straight line = high pressure, but straight line drag = VERY low rear pressure!

[jrandom]

slow person on a gsx1400 will benifit from a complely different set up from a fairly rapid dude on a R1 etc

Quite true, actually. We were discussing this via MSN when the thread went up.

I run Betty at 36 front 40 rear, because I'm a total nana on the throttle and I don't tend to warm up the rear tyre much on the road. I also get the shits if the rear tyre flexes in corners, so I prefer to have it as rigid as possible without actually forcing it to skitter around.

There are tyre life benefits to riding the way I do - I've had 13,500km out of my current set of Pilot Road 2s.

[madandy]

I put 'depends' because well...it depends.
If I had rear wheel traction issues I'd lower my rear tyre pressure and if that meant it was running a lower pressure than what was working for me on the front tyre then so be it. Same applies for the front.

Assuming you have the suspnsion set up well for starters of course

[Marknz]

If you go to a ride day in Aussie, particularly the Eastern Creek and Phillip Island Ride Days, they tell you in no uncertain terms at the beginning of the day to go 30 front and 30 rear. But that is for ride days, and generally your ambient and track temperatures will be warmer there than here.

My GSX-R600 tyre sticker tells me to run 36/36 for solo riding, and 36/42 when two-up.

[trumpy]

The Continental website lists my S4 as 35F/39R for the Sport Attacks so I have used this as a starting point. I have found that if I lower the rear pressure too much the handling starts to suffer. Some of this may be due to tired suspension and/or less than ideal setup. Once Robert Taylor has rebuilt my suspension then it will be interesting to see what what differences changing the front/rear pressure balance does.

[The Stranger:Me]

Well they don't seem to square of so quickly.

Hmm I find the opposite.
I run 32 front and 27 rear on the road for normal riding and commuting. Any higher and the rear disappears before my eyes (figuratively).

Point is, I think it really does depend on the tyre, the bike and the rider and there is no hard fast rules. One should keep an open mind.

[saltydog]

On the R1, 32 in the front, 34 in the rear. My last tyre, Dunlop D208? lasted 3500ks on the road, I thought that went a big quick. The pressure is so dependant on all these other variables. Thats why biking is so bloody good, every ride is a new one. I'd definiatley put higher pressure in the rear if I was doubing. But my new seat cowl and exhaust hanger got rid of the possibilty of ever being passenger any more.
And down to 30 in the front if I was fangin requiring a bit of extra rubber on the road.
First set of these 2CT's, seem quite good. Cant complain, seem to perform and with it appears more wear in them.

[Forest]

Perhaps, but surely the larger air quantity
Weight distribution is often quoted by the manufacturer. In the case of the Fazer they quote 51% front 49% rear. I assume (though I realise assumption is the mother of all fuck ups) that is with a rider on board, if not, why quote it as it would be useless information as a bike can't be ridden without a rider. Therefore you have roughly equal weight distribution. The forces under decelleration are greater than accelleration, so were a variance in presure required for accelleration, surely they would be required for decelleration and require greater pressure in the front.

Weight distribution figures are quoted without a rider on board.

It is basically marketing wankery ... along the same lines as quoting dry weights.

[Grub]

The geometry of each bike is different and calculated my super-computers, the best money can buy. So ....

- Use the tyres specified for that bike
- Use the pressures specified for that bike.

On both CBR's I've owned the pressures are 36F, 42R and I can immediately feel a drop of 2psi. On Nasty's GSXF750 its 36/36 so the poll could mislead the unwary into dangerous territory.

[cowpoos]

Weight distribution figures are quoted without a rider on board.

It is basically marketing wankery ... along the same lines as quoting dry weights.

not really...its of alot of interest to racers and people who understand its relivence.

[homer]

more psi less heat
less psi mpre heat

in other words more heat ......less tire life and less heat .....more tyre life

i dont have the dollars to try it all
so 39 psi front and 40 psi rear
r6 roadtecs
near 6000 km now and just showing a slight flat on the rear
the front well its a crappy pilot road , its got some shoulders now , done about 8000km since ive had the bike , on the bike when i got it .
I think itll be good as for another 10000km piss easy .
Heaps tread left on the front , theres a new road tec sitting waiting to go on the front.

[Ocean1]

I'll ad some more numbers, Pilot Sports on a 179Kg Buell (and bike weight's definitely a major factor) really don't like less than 30psi on the front, you can feel them start to get unstable and distort. They feel fine at anything between 34 and 38psi. I've found 36psi both ends is a good compromise.

I wondered, (belatedly) if this was all about sportsbikes, general road bikes, or bikes in general... 'Cause all the numbers quoted so far are wayyy over the top off road.

Oh, and the drag slicks are run that soft because, firstly the silly-putty compounds grip much better with the larger contact patch, (and little or no lateral load means they can get away with it) and secondly one of the characteristics they're looking for is a huge increase in diameter over the run, to provide progressive gearing.

[The Stranger:Me]

Weight distribution figures are quoted without a rider on board.

It is basically marketing wankery ... along the same lines as quoting dry weights.

Hmm, after xerxesdaphat's post my interest was piqued so I measured the Fazer.
I guess it was dumb luck that Yamaha got it pretty spot on with me on board. Sure I could sit up and shift it back or lean forward and move the weight forward, but for my normal riding position the claimed 51% front 49% rear is remarkably accurate.

On the face of it one would wonder how it helps marketing, which is better? more of a front or rear bias?
Is there a magical number?

However the fact remains, we were discussing wieght difference on the tyres and in that regard it is pertinent.