Tyre Pressures Street and Track.

V

Vince

Hero member
Nearly as fun as an oil thread. Maurice's comment in the Philip Island threds got me thinking about this stuff,
Quote
I managed to get some stability out of my 78 Jota in her standard Ceriani suspension as the day wore on I just kept dropping the tyre pressures.

I was reading a thread elsewhere about track day tyre pressures that surprised me a lot. I have pretty much zero track time and what I had was so much fun but I did notice I was destroying my rear tyre. I am talking about tearing strips of it. That's using my normal absolute analy checked every ride pressures of 37psi front and 40psi rear. That is on Bridgestone T32. The track day people were saying they run high 20s as ripping on a track heats tyres and that ups pressure a lot. That I found really odd, if I ran 29ish psi on the road my bike would wallow like a drunken sailor. So what's the go with track riding and tyre pressures? Love to hear more about this. BTW I think there is talk about the Sydney Guzzi people running a track day at Eastern Creek in 2024.
 
Forget the comparison. The track day people told you the correct track pressure. On the road you need far more, as it is virtually impossible to ride on the road like you would on the track. You are not braking into a corner every so many seconds as hard as your brakes/tyre allow, getting the absolute maximum corner speed you can and accelerating as hard as you can off it. 40psi on the track would have you skating all over the place.
 
Vince said:
I have pretty much zero track time and what I had was so much fun but I did notice I was destroying my rear tyre. I am talking about tearing strips of it. That's using my normal absolute analy checked every ride pressures of 37psi front and 40psi rear.
Click to expand...
sounds like you were cold tearing the shit out of the tyre
 
It was spinning up and sliding, great fun, it would have cooked the rear really quickly. So what does much lower pressures do to stability on a track/
 
Its pretty bloody basic Vince.. on the track you generate a lot more heat and pressure in the tyre due to the loads you are putting on the tyres.. so you start with lower pressures and monitor the gain to optimum feel and grip..

:cool:
 
So do they end up at typical road pressures after a few laps, do you ride through that first bit of low pressure with the resultant instability before they heat up and come to pressure? For example, you head out at 29 psi cold and end a session at mid to high 30s. Not to sure I would like to hit turn one at Eastern Creek on a cold 29psi tyre.
 
In the first instance check with the manufacturer on their recommended tyre pressure for track use. At the circuit set the pressure below this level , this will depend on track temperature, higher the temperature, lower the initially pressure. So say track temp is 25c knock 4psi out of the rear, 2 out of the front say. Go out , run several laps building speed, come in check pressure, adjust accordingly. If using tyre warmers you can of course pre heat the tyre, a must with slicks. Road tyres warm up quickly because of the rubber tread moving and generating heat. Of course experience helps!
Andy
 
Dave and I started with 32 front and back for the first session and then lowered the pressure to 30 for the second and by the time we went out for the third session we were down to 28. Tyres were hooking up great at those pressures and like Dave said earlier just go for it on the first lap😂👍. We did check the pressure the next day and they were bang on 28👍 Dave was running Bridgestone bt46’s and I was running a pair of bt016’s. Both very handy tyres for the track at our skill level😂😂
Tom
 

Attachments

  • IMG_1732.jpeg
    IMG_1732.jpeg
    195.1 KB · Views: 25
  • IMG_1730.jpeg
    IMG_1730.jpeg
    211.3 KB · Views: 25
  • IMG_1733.jpeg
    IMG_1733.jpeg
    182.2 KB · Views: 26
  • IMG_1735.jpeg
    IMG_1735.jpeg
    190.9 KB · Views: 26
Tom, what was stability like at 28psi for the first few corners? Did it take long to feel comfortable?
 
I was running 17s (Sportmax Q3s). On the road I run 30/32 F/R cold. I set both to 30 cold for my first 'learn the track' session and had 33 F/R when I came in - dropped 3psi in both. Next sesh I was getting into it quite a bit more and again had 33/33 F/R and dropped a further 3 psi in both. Out of interest I'll check what my tyres are reading cold now. Can't compare tyres, but the SFQ was very stable at speed - zero hint of a wobble, and I'm estimating I was hitting 220 when I grabbed the brakes into Turn One. If anyone thinks that's a stretch for a road-going twin ask Maurizio :cool:

Maurizio, the other factor that could have helped was relaxing more with each session, a lighter grip on the bars as we get used to the heart-in-mouth stuff the Island can dish out - can definitely help.

I've purchased a couple of pics - I'll resize and post.
 
I started my track days with 27 f/r, after 15 mins they were 30, probably lost a little on the trip back into the pits.
Couldn't fault the handling of the Motodd. Did one easy lap then got on the gas. Tyre warmers seem to be the go when cruising the pits.
I was surprised how hot the tyres were after removing the warmers.
 
I need to start thinking about a set of tyres for the SFC. Want something really sticky as the bike will only be used on the track.
Even race tyres would be an option. Suggestions??
 
motoddrob said:
I started my track days with 27 f/r, after 15 mins they were 30, probably lost a little on the trip back into the pits.
Couldn't fault the handling of the Motodd. Did one easy lap then got on the gas. Tyre warmers seem to be the go when cruising the pits.
I was surprised how hot the tyres were after removing the warmers.
Click to expand...
we aim for 90C when removing the tyre warmers
trick is to get the rims hot as well, not all tyre warmers achieve that
 
Even a humble BT45 can work well on a track. But I reckon a more demanding rider will quickly overwhelm it.

IMG_0478.JPG

Trackday in July with rather low 20's ambient and even lower track temps. Ran the front at 2 bar/28psi instead of my usual 2.5/35 for road riding, but didn't bother to check warm pressure. Took it easy from cold for half a lap and just went for it. Track surface wasn't as confidence inspiring as Spa or Nurburgring, but I got used to it as the day wore on, didn't even have a single arse clencher. Ran wide a couple of times because of my poor physical condition though, concentration waned pretty quick when I tried harder.

I remember Dunlop technicians run over to our pit at Daytona '96 when we were running Metzelers, as opposed to everybody else on either Dunlops or Avons (all specially formulated for the H-D SuperTwins series) . They were curious and asked if they could measure our tyre temps when a rider rolled in during practice. I was amazed at the difference between LH to RH side! The pit entrance is immediately after the run off the banking, a long , fast left, left side of the front tyre was something like 30°F hotter than the right. Can't remember the absolute temps though, too long ago...

piet
 
redax5 said:
did they give you times at all ?
we run 1min, 46.9 secs at PI, so far
Click to expand...
I'm so far off race pace it's not worth the trouble to put a watch on me, Red, but a mate timed a few on his iPhone and I didn't even get below 2:10 in my 20(?) laps total, which is still 5 sec slower than i went 25 years ago on a slower bike. As mentioned I never got a clean lap, either from carefully passing slower riders or missing an apex, running wide, fukking up generally ... and then of course there's the little voice in your head telling you how long it took to build this bloody moto! I was dropping 4-5 sec each session and finally starting to relax and think clearly, so reckon I could have at least got down to my 43yo self's provisional best time. Finding 10 sec to even go under 2 minutes does my head in ... then I see pics of the FAST group and a guy on a Panigale scraping his knees and elbows in Southern Loop - my mate clocked him at only 1.53! Fookin' 'ell!

Matty's time on the Mule is serious!
 
Last edited:
You must log in or register to reply here.
Back
Top