Slicks, What Air Pressure should I run?

[Pumba]

Hey, as the title says.

Managed to pick up a set for my FXR project, fitted them, and just wanting to know whats a good starting pressure to run them at, at Mt Wellington.

I was thinking about 20-25 PSI, am I wright or wrong.

[gammaguy]

as a rule of thumb when i race i look for a 4psi pressure rise from cold to hot.(when using air)starting as a baseline you sound about right but i have not raced a bucket for a loooong time.the seat of the pants counts for a lot too

[CB ARGH]

From what I have been told by a bird in a tree...

The lower the pressure, the quicker it heats up, and more of the wheel will be on the surface. However if it's too low, it will drag along the road, potentially slowing you down and becoming very poor with fuel economy. This is better for riding in the wet.

The higher the pressure, the slower it is to heat up, less of the wheel will be on the surface. However, the less drag it will have on the road, and potentially more fuel economic.

Don't take my word for it though. There's some smart guys on this forum who could help you a lot more, just adding my two cents worth though.

Churr!

STEVE

[Ivan]

Depends what tires you are running. Dunlops

are arpund 28 rear 22 front I think cant remember fully aint done tire pressure on 125 in ages

But I mean some tires using example here COnti Race attack 22PSI rear tire and 28 PSI front

[Buckets4Me]

I was always told that it is a psi or 2 above the presure that lets the tire slide easily or something like that
i would shit myself trying to find that point (i got this backwards it use to be you added pressure till they slid then backed it of 2 psi)


but am sure that they run 18-20 psi in the slicks at Mt wellington {bit more air when it is wet so the tire presses down threw the water}
it is a lot lower than for road tires like tt900's

then the fast guys on slicks are mad

just ask a few next time you are there they have a compressa just take a tire pressure tester with you
best to use your own and use the same one every time

[SHELRACING]

Hey, as the title says.

Managed to pick up a set for my FXR project, fitted them, and just wanting to know whats a good starting pressure to run them at, at Mt Wellington.

I was thinking about 20-25 PSI, am I wright or wrong.

Assuming you have removed the Tubes. Most riders run at 19 - 20 PSI. I've run 19 PSI at 3 different tracks and that works best for me.

The only problem you'll have is if you are still using tubes 19PSI is not enough to stop tubes moving and eventually punctures.

Got any pics of the bike ??

[Buddha#81:Me]

i was running 24-26psi in slicks on my FXR, last meeting I was recomended to go up to 28psi front and rear and the bike felt pretty good.

I think below 20 psi you will be running into troubles.

[nudemetalz]

I run around 22psi front and 25 psi rear in the slicks on Lady P.

[Pumba]

Thanks guys, you have just confirmed what I already thought

Got any pics of the bike ??

No finished pics, still got to do a bit of tidying up with the wireing. Doesnt look to didferent from a standard FXR at the moment though

[Buckets4Me]

tubes 19PSI is not enough to stop tubes moving and eventually punctures.

heavy duty tubes for dirt bikes
dont ask me where you get 17's from
and also grinding the spokes down so they dont poke threw to far lol
and lots of rim tape's

come have a talk to every one next time
they will tell you all the secrets and where to get stuff from
cycletreds is always a good start and they are good with info 2

[k14]

On the RS125 I run between 27 and 29 psi in my slicks. I do the same on the bucket. I think 20psi is way way too low for one of those tyres (not that I have any proof of that though). I think if you run too low pressure it will effect both the handling and straight line speed, too much drag and the tyre is too deformed on the surface. If anything I would tend to run closer to 30psi on a bucket cause a RS125 is 30+kg lighter than my bucket. Each to their own though.

[xwhatsit]

heavy duty tubes for dirt bikes
dont ask me where you get 17's from

From what I've read (and seen people do), tubes seem to be pretty tolerant to being used as the `wrong size'. Plenty of offroad bikes out there with 18" rims -- I don't think using an 18" tube in a 17" tyre is going to be too much hassle.

[F5 Dave]

ok time for the definitive answer, and just to be a prick I'll finish with a question.

The chch guys are right for their tracks you run more pressure, the speeds are much much higher. I'd dispute the same as RS as the speeds are lower. At the BOB I was running pretty low pressures & the tyres were not marking up like they were working, but the 50 is very light (less than an RS) & it was stupidly cold.

At kart tracks you get away with running tyres too soft so they are actually deforming. Some of the light guys on 50s on old Yokos used to run 16psi! They ran tubes & threw them away often.

19-20 on Bridgestones seems good for me & I run a pound or so more on the Dunlops. Less if freezing cold.

But I'd also add a pound or two if you are, um how can I put this? or your bike is a porker. Then try it, add & subtract & see what you like. Try & determine the diff between squirm & slip.

OK the question. . .um, no I don't really have one.

[FROSTY:Me]

As per usual Dave beat me to it-
Short version-SLIPWAY AND MT WELLINGTON- start point 18psi front and rear.
Ruapuna and Taupo 22-24 start point.
Dug out my racenotes from way back when and on the Yoki sprints I was running 17psi at a winter meeting at mt welly
To remind this old man--Dave what happened when we ran trailbike rimlocks back in the spoked wheel days?
- I remember trying it but farked if I can remember the verdict.

[F5 Dave]

I think I did try when running a skinny steel rim at the rear. Decent size rim & problem doesn't exist as tyre not bowed. Inner tubes are dumb anyway.