Ekona Posted October 31, 2011 Share Posted October 31, 2011 Didnt realise this would cause such a debate! I inflated my tyres to 36 front and 37rear just after i left home,and have to say that they were at 33F+34R before. After a few laps,i felt the car wasnt right,so checked the pressures,and they were over 40 all round,so dropped them to 35 all round,and the car felt so much better,and more planted,especially round the fast corners. I was understeering before,and after the pressure drop,it just gripped and felt alot better. Did you reset the pressures after the day? Quote Link to comment Share on other sites More sharing options...
Daryl Posted October 31, 2011 Author Share Posted October 31, 2011 I havnt yet no,as havnt been out in the car since,but was planning on checking them on the way to work this afternoon. Should i keep them at 33-34,which is what they were at to start with? Quote Link to comment Share on other sites More sharing options...
Ekona Posted October 31, 2011 Share Posted October 31, 2011 Put them to whatever you're happy with, but be aware that whilst low pressures will give you more grip due to more tyre being in contact with the road, you'll also get increased wear. Too high and you'll end up with the middle bald as well, so it's a balancing act really. If you felt comfortable with the 33F34R combo then I'd stick with that. Personally I think that's too low for the floppy sidewalls of the Falkens and would set them to the 36F37R I mentioned earlier, but in all honesty you're not going to go far wrong in terms of tyre wear/damage anywhere in the 30-40 psi range. Quote Link to comment Share on other sites More sharing options...
Chris`I Posted October 31, 2011 Share Posted October 31, 2011 So why do the likes of car limits tell people to inflate their tyres to max. Andy only says that to minimise tyre wear as North Weald is so abrasive. Having heard it from the man himself as I asked why we do it - he told me it was mainly to stop the tyre from being able to roll under the rim as North Weald is so abrasive and grippy. With low profile tyres a lot of the guys run, you dont have to be sliding sideways much for them to grip and pop under the rim, completely buggering the wheel. Also it makes the tyre balloon which reduces grip meaning the cars will spin at lower speeds on the courses, which in turn means you dont have to go as fast to get used to the car sliding as it would on the road. He told me the correct way to pressure your tyres is to look for the little triangles at the edge of the tread. If you are under it (ie wear is inside of the markings) you can lower pressure. If you are over them (ie wear is between them and the rim, actually using the sidewall) then you should increase pressure. A friend in his Evo didnt pump his tyres up as much as he should and actually we saw the wear on the tyre wall itself Increasing it a few more PSI made it go back behind the triangles and the car handled much better. Pumping it up to max would have meant the tyres had less grip due to ballooning, but would have protected the rims further and also not meant he'd have to go so quick to induce slide. Quote Link to comment Share on other sites More sharing options...
Ebized Posted October 31, 2011 Share Posted October 31, 2011 If you felt comfortable with the 33F34R combo then I'd stick with that. Personally I think that's too low for the floppy sidewalls of the Falkens and would set them to the 36F37R I mentioned earlier, but in all honesty you're not going to go far wrong in terms of tyre wear/damage anywhere in the 30-40 psi range. Having used the 452's on the 19" wheels I had on last 350 I would say go for 37, especially if you like to push on like SV Quote Link to comment Share on other sites More sharing options...
Chris`I Posted October 31, 2011 Share Posted October 31, 2011 Also Daryl, dont you have a few F1 engineers you can ask Quote Link to comment Share on other sites More sharing options...
Beavis Posted October 31, 2011 Share Posted October 31, 2011 If you felt comfortable with the 33F34R combo then I'd stick with that. Personally I think that's too low for the floppy sidewalls of the Falkens and would set them to the 36F37R I mentioned earlier, but in all honesty you're not going to go far wrong in terms of tyre wear/damage anywhere in the 30-40 psi range. Having used the 452's on the 19" wheels I had on last 350 I would say go for 37, especially if you like to push on like SV I run my Toyo's at 37psi all round to compensate for the softer sidewalls, but last April on the Wales recce they had risen to 41psi all round by time we got to Betws-y-coed for a lunch stop! Yes it was a warm day but i cant say we drove at track speeds on the public roads. Colin can vouch he was there when i re-checked the pressure's with my Michelin digital guage. Quote Link to comment Share on other sites More sharing options...
Ekona Posted October 31, 2011 Share Posted October 31, 2011 Bear in mind that all OEM recommended pressures are for cold tyres, and they expect them to heat up during use. As such, a when-warm temp of 40+ is to be expected especially on a sports car when pushing on. FWIW I've never checked the warm temps of the tyres on the 911, as it feels planted and stable and predictable and because of that I know the pressures are correct (although I do deviate 2 psi from the recommended Porsche pressures at the front as that's how I like my cars setup). Because everyone has different driving styles and outside temps vary greatly over the course of a year I wouldn't pay too much attention to absolute pressures when warm, it's more important to get the cold setting right and then adjust relative to how the car feels when on track. On a very hot track day in the middle of summer then you might want to drop 5psi all round, but on the same track the next day when it's overcast you may want to drop just 2psi or even just leave them alone if there's a bit of rain from the night before. Predictability is the key to fast, smooth driving whether that's on road or track IMHO. Quote Link to comment Share on other sites More sharing options...
docwra Posted October 31, 2011 Share Posted October 31, 2011 FWIW I've never checked the warm temps of the tyres ....... because everyone has different driving styles and outside temps vary greatly over the course of a year I wouldn't pay too much attention to absolute pressures when warm, it's more important to get the cold setting right and then adjust relative to how the car feels when on track. This, 100%. Even when drifting (which tyre pressures affect more IMO, we are changing rear tyres every few laps and grip is not constant) its rare for me to change the pressure more than once a session, and when I do its not a set amount i.e. from 34 to 36, its just "a bit more" or a "a bit less" until it feels better. I seem to be agreeing with Ekona rather a lot these days ....... Quote Link to comment Share on other sites More sharing options...
Ekona Posted October 31, 2011 Share Posted October 31, 2011 Scary, isn't it?! Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted October 31, 2011 Share Posted October 31, 2011 So you go out on your 1st track session with say 34 psi frt 36psi Rr, then do your 1st session you come back in the pressures have gone up to say 38psi frt 42psi rear , you lower the pressures to 36psi frt and 38psi rear this is your warm tyre pressure , then you do another session do the tyres not gain anymore pressure? if they do do you leave them as is or do you lower the pressure to your warm temperature pressure? Quote Link to comment Share on other sites More sharing options...
Ekona Posted October 31, 2011 Share Posted October 31, 2011 I probably wouldn't touch them again if it were me, but that depends very much on the weather conditions and how the track is changing. I get quite lazy on trackdays tbh and I'll normally just find a setting that feels comfortable for the whole day and stick with it, and often I won't change tyre pressures at all from cold first thing. I don't have a particularly aggressive driving style so tyre wear is minimal for me, and if I overheat the tyres (which I have done, but only the once) it serves as a reminder that I've been out too long and should be coming in for a break anyway. Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted October 31, 2011 Share Posted October 31, 2011 and if I overheat the tyres (which I have done, but only the once) it serves as a reminder that I've been out too long and should be coming in for a break anyway. So the tyre pressure will still climb then? the only trouble if you do get to the point where the tyre pressures are constant , the 1st few laps out the pressures will be low and the car will not feel right so you need to be careful. Quote Link to comment Share on other sites More sharing options...
Ekona Posted October 31, 2011 Share Posted October 31, 2011 Agreed, but then you should be doing a couple of warm-up laps for both the car and the driver anyway. Quote Link to comment Share on other sites More sharing options...
andlid Posted October 31, 2011 Share Posted October 31, 2011 I would keep lowering the pressure... Would like to know what to have on pe 50 on 18. Quote Link to comment Share on other sites More sharing options...
andlid Posted October 31, 2011 Share Posted October 31, 2011 Agreed, but then you should be doing a couple of warm-up laps for both the car and the driver anyway. Doesnt most trackdays that arent open pitlane have a one lap warmup? Quote Link to comment Share on other sites More sharing options...
Neilp Posted October 31, 2011 Share Posted October 31, 2011 Agreed, but then you should be doing a couple of warm-up laps for both the car and the driver anyway. Doesnt most trackdays that arent open pitlane have a one lap warmup? usually a sighting lap. No great speed and not enough to get heat into tyres etc. My tyre pressures were set at 35psi before going on track and after 8 laps the were at 42psi on one side and 40 on the other. Best solution is to nitrogen fill. Cheap and an easy fix and helps on normal motorway journeys etc. Quote Link to comment Share on other sites More sharing options...
andlid Posted October 31, 2011 Share Posted October 31, 2011 Agreed, but then you should be doing a couple of warm-up laps for both the car and the driver anyway. Doesnt most trackdays that arent open pitlane have a one lap warmup? usually a sighting lap. No great speed and not enough to get heat into tyres etc. My tyre pressures were set at 35psi before going on track and after 8 laps the were at 42psi on one side and 40 on the other. Best solution is to nitrogen fill. Cheap and an easy fix and helps on normal motorway journeys etc. mmm nitrogen thats a tad overkill IMO. Ill keep track on my pressures I just need a good baseline (cold setting to work on, Im guessing the sides will be all over the place so best bring my air compressor for the ride home!) Quote Link to comment Share on other sites More sharing options...
Neilp Posted October 31, 2011 Share Posted October 31, 2011 Agreed, but then you should be doing a couple of warm-up laps for both the car and the driver anyway. Doesnt most trackdays that arent open pitlane have a one lap warmup? usually a sighting lap. No great speed and not enough to get heat into tyres etc. My tyre pressures were set at 35psi before going on track and after 8 laps the were at 42psi on one side and 40 on the other. Best solution is to nitrogen fill. Cheap and an easy fix and helps on normal motorway journeys etc. mmm nitrogen thats a tad overkill IMO. Ill keep track on my pressures I just need a good baseline (cold setting to work on, Im guessing the sides will be all over the place so best bring my air compressor for the ride home!) nitrogen is only a quid a tyre from qwik-fit mate Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted October 31, 2011 Share Posted October 31, 2011 Agreed, but then you should be doing a couple of warm-up laps for both the car and the driver anyway. Doesnt most trackdays that arent open pitlane have a one lap warmup? usually a sighting lap. No great speed and not enough to get heat into tyres etc. My tyre pressures were set at 35psi before going on track and after 8 laps the were at 42psi on one side and 40 on the other. Best solution is to nitrogen fill. Cheap and an easy fix and helps on normal motorway journeys etc. mmm nitrogen thats a tad overkill IMO. Ill keep track on my pressures I just need a good baseline (cold setting to work on, Im guessing the sides will be all over the place so best bring my air compressor for the ride home!) nitrogen is only a quid a tyre from qwik-fit mate Nitrogen moves as well Neil, trust me. Choice of tyre pressures are down to the individual and the type of tyres they run and the type of track and whether it is open pit lane. Most run at a pressure that suits there driving style and what they are comfortable with. At Knockhill for instance, running the Zed on open pitlane, if I am running "standard" tyres then I start cold at 35psi all round. After a few warm up laps and then a few spirited laps I will come in and check the pressures which on a summer's day will be circa 44psi. I will reduce all to 35psi except the L/H front which I will reduce to 37psi. I will then have a serious 10 lap session and the pressures will be rechecked and they will more than likely be back up to around 40 psi. I will reduce again to 35/37 and that will be me for the rest of the day. The one thing that you must watch with this strategy is that if you have an extended cool down period in excess of 15 minutes then you must be extremely carefull on your next first few laps as the pressures will be extremely low, however once you are back in the groove you will soon be back up to 35/37. I use the same strategy for slicks however the numbers are different. Alex Quote Link to comment Share on other sites More sharing options...
Neilp Posted October 31, 2011 Share Posted October 31, 2011 I have big bottles of OFN sitting in my garage for the tyres lol It does move, nowhere near as much as normal air though. Much much more stable. Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted October 31, 2011 Share Posted October 31, 2011 I have big bottles of OFN sitting in my garage for the tyres lol It does move, nowhere near as much as normal air though. Much much more stable. More stable because it is probably a 90/10 mix once in the tyre unless you run a vac. which then may give you 100% nitrogen Quote Link to comment Share on other sites More sharing options...
Chris`I Posted October 31, 2011 Share Posted October 31, 2011 I have big bottles of OFN sitting in my garage for the tyres lol It does move, nowhere near as much as normal air though. Much much more stable. More stable because it is probably a 90/10 mix once in the tyre unless you run a vac. which then may give you 100% nitrogen Would a vac even get out most of the air? Cant see a tyre deforming enough on the rim to suck out the air. You'd need to do a few cycles to try and flush out the air. Would be a right PITA - easier just to check the pressures Sure I've seen setups before where they have 2 valves so they can flush them through. Quote Link to comment Share on other sites More sharing options...
Neilp Posted October 31, 2011 Share Posted October 31, 2011 I have big bottles of OFN sitting in my garage for the tyres lol It does move, nowhere near as much as normal air though. Much much more stable. More stable because it is probably a 90/10 mix once in the tyre unless you run a vac. which then may give you 100% nitrogen Would a vac even get out most of the air? Cant see a tyre deforming enough on the rim to suck out the air. You'd need to do a few cycles to try and flush out the air. Would be a right PITA - easier just to check the pressures Sure I've seen setups before where they have 2 valves so they can flush them through. my vac pump vacs down beyond 2 torr so it could sook the air out but the tyre will deform. Easier just to empty and fill with nitrogen leaving a couple of litres of uncompressed air in and mix it with the nitrogen. What your talking about it pro stuff lol. I actually have no idea of the setup you are talking about but having majority nitrogen will help but may be a pain in the rectum carrying a 20kg nitrogen cylidnder to the track to top up before leaving. Quote Link to comment Share on other sites More sharing options...
andlid Posted October 31, 2011 Share Posted October 31, 2011 sound alex Quote Link to comment Share on other sites More sharing options...
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