Tyre Pressures
Discussion
I have just had 2 Falkens fitted to the rear of my Chim.
Tyre guy said he thought 24psi for the rears was way too low, and put them at 32psi. Said to see how they feel. Well they don't feel right!
Manual says 22psi front and 24psi rear. I’ve checked previous posts and it seems the popular vote goes for 22psi front and 26psi rear. Do this sound about right from experience?
Cheers BB
Tyre guy said he thought 24psi for the rears was way too low, and put them at 32psi. Said to see how they feel. Well they don't feel right!
Manual says 22psi front and 24psi rear. I’ve checked previous posts and it seems the popular vote goes for 22psi front and 26psi rear. Do this sound about right from experience?
Cheers BB
I have falkens on the rear and found they run best at 26 in the winter, 27 in the summer. Below that they go a bit mushy, above that and grip starts to fall away. I am only an average driver and I was very surprised to find I could tell the difference between 26 and 27 psi !
ETA: When I first bought the chim the previous owner had all 4 tyres up at 32psi, it was like skating on ice !
ETA: When I first bought the chim the previous owner had all 4 tyres up at 32psi, it was like skating on ice !
Edited by bigdods on Thursday 7th February 10:31
WazzaL said:
I have Toyo's fitted, and when the car went in for a service with TopCats, they altered the pressures to 25psi all round.
Assume they know better than I do, and the feel is definately much better than when the pressures were higher.
Toyo's T1r & T1s have softer side walls than the old Bridgstones so need a couple of psi extra to increase rigidity. The pressures in the book refer only to Bridgstone.Assume they know better than I do, and the feel is definately much better than when the pressures were higher.
Tyre pressures vary across different models of tyres, I wouldn't make direct comparisons... Can't really recall any being outside 20-28psi though, which at least limits the range. Its the old change one thing at a time & test it to find what works best for you - half the fun of owning the cars is being a test driver IMHO 
Dave
Dave
Went out at lunch time and got some grief from a t**ser in a BMW. I gave mine some encouragement, but the tyres were not at all happy. The guy probably now thinks TVR's are not upto the performance of his German p&J.
Anyway, I've put them at 24f and 26r. Seems much better, but I will give it some beans later this aft and see how she goes.
Anyway, I've put them at 24f and 26r. Seems much better, but I will give it some beans later this aft and see how she goes.
BatleyBoy said:
Went out at lunch time and got some grief from a t**ser in a BMW. I gave mine some encouragement, but the tyres were not at all happy. The guy probably now thinks TVR's are not upto the performance of his German p&J.
Anyway, I've put them at 24f and 26r. Seems much better, but I will give it some beans later this aft and see how she goes.
What were they at before?Anyway, I've put them at 24f and 26r. Seems much better, but I will give it some beans later this aft and see how she goes.
nikman said:
BatleyBoy said:
Went out at lunch time and got some grief from a t**ser in a BMW. I gave mine some encouragement, but the tyres were not at all happy. The guy probably now thinks TVR's are not upto the performance of his German p&J.
Anyway, I've put them at 24f and 26r. Seems much better, but I will give it some beans later this aft and see how she goes.
What were they at before?Anyway, I've put them at 24f and 26r. Seems much better, but I will give it some beans later this aft and see how she goes.
BatleyBoy said:
I have just had 2 Falkens fitted to the rear of my Chim.
Tyre guy said he thought 24psi for the rears was way too low, and put them at 32psi. Said to see how they feel. Well they don't feel right!
Manual says 22psi front and 24psi rear. I’ve checked previous posts and it seems the popular vote goes for 22psi front and 26psi rear. Do this sound about right from experience?
Cheers BB
Well they are new tyres so they will need possibly 50-100 miles before they bed in anyway....then you will have a better idea what pressures to put them at. My Falkens are brilliant but needed about 50-60 miles of curing (get them reasonabbly hot and then let them cool down and then hot again) to bed them in before they felt right. I have them at about 24/25 at the rear. If you start to burn rubber as such before they have bedded in you will simply be shortening the life of your tyres!Tyre guy said he thought 24psi for the rears was way too low, and put them at 32psi. Said to see how they feel. Well they don't feel right!
Manual says 22psi front and 24psi rear. I’ve checked previous posts and it seems the popular vote goes for 22psi front and 26psi rear. Do this sound about right from experience?
Cheers BB
22 front and 24 rear for normal every day driving.
26 front and 28 rear for track day driving and those special spirited driving days
One word of warning, if you have an accident and the Police check your tyre pressures and they are about that in the hand book, you may be in for the shock of your life.....
Yeap its not normal pressure and your not insured, any way to get out of paying for repairs.
This has happened to a number of people with performance cars across the UK and is a not pleasant.
Easy answer, leave the book at home and pray the cops are thick....
Colin L
26 front and 28 rear for track day driving and those special spirited driving days
One word of warning, if you have an accident and the Police check your tyre pressures and they are about that in the hand book, you may be in for the shock of your life.....
Yeap its not normal pressure and your not insured, any way to get out of paying for repairs.
This has happened to a number of people with performance cars across the UK and is a not pleasant.
Easy answer, leave the book at home and pray the cops are thick....
Colin L
There are a lot of numbers being thrown in here but with no mention of which tyres they relate to.
The effect of warming should also be considered. When tyres warm up the pressure increases. The cold set pressures in the book do not represent the optimum driving pressure, they are the cold set pressures needed to generate the higher 'hot' pressures that these cars need for fast use. That hot pressure can be several psi higher than the 'cold' set pressure.
Using nitrogen as supplied by many tyre monkey outlets these days is also bad. This nitrogen is dry and the combination of nitrogen coefficient of expansion and lack of liquid means that the pressure will not increase with heat as much as it would with air. The important pressures aren't the book pressure, they are the hot pressure that those cold set pressures were calculated to provide.
spend said:
Tyre pressures vary across different models of tyres, I wouldn't make direct comparisons... Can't really recall any being outside 20-28psi though, which at least limits the range. Its the old change one thing at a time & test it to find what works best for you - half the fun of owning the cars is being a test driver IMHO
Dave
Dave puts it very well here, the Bridgestone SO series tyres were quite rigid and so using other makes of tyre means that those pressure settings in the book are inappropriate. I'm sure our cars will be OK at 22/24 but they won't be as good as they can be. Dave
The effect of warming should also be considered. When tyres warm up the pressure increases. The cold set pressures in the book do not represent the optimum driving pressure, they are the cold set pressures needed to generate the higher 'hot' pressures that these cars need for fast use. That hot pressure can be several psi higher than the 'cold' set pressure.
Using nitrogen as supplied by many tyre monkey outlets these days is also bad. This nitrogen is dry and the combination of nitrogen coefficient of expansion and lack of liquid means that the pressure will not increase with heat as much as it would with air. The important pressures aren't the book pressure, they are the hot pressure that those cold set pressures were calculated to provide.
Edited by tvrbob on Friday 8th February 07:46
tvrbob said:
There are a lot of numbers being thrown in here but with no mention of which tyres they relate to.
The effect of warming should also be considered. When tyres warm up the pressure increases. The cold set pressures in the book do not represent the optimum driving pressure, they are the cold set pressures needed to generate the higher 'hot' pressures that these cars need for fast use. That hot pressure can be several psi higher than the 'cold' set pressure.
Using nitrogen as supplied by many tyre monkey outlets these days is also bad. This nitrogen is dry and the combination of nitrogen coefficient of expansion and lack of liquid means that the pressure will not increase with heat as much as it would with air. The important pressures aren't the book pressure, they are the hot pressure that those cold set pressures were calculated to provide.
All true but my understanding is that car handbook tyre pressures all reference 'cold' tyres - to check 'hot' tyres is way too variable. Do you check after a 100 mile fast motorway trip, after hooning around back roads for half hour or after a short trip down the road to buy a newspaper? All are likely to give you pressures that will easily differ by up to 10psi.spend said:
Tyre pressures vary across different models of tyres, I wouldn't make direct comparisons... Can't really recall any being outside 20-28psi though, which at least limits the range. Its the old change one thing at a time & test it to find what works best for you - half the fun of owning the cars is being a test driver IMHO
Dave
Dave puts it very well here, the Bridgestone SO series tyres were quite rigid and so using other makes of tyre means that those pressure settings in the book are inappropriate. I'm sure our cars will be OK at 22/24 but they won't be as good as they can be. Dave
The effect of warming should also be considered. When tyres warm up the pressure increases. The cold set pressures in the book do not represent the optimum driving pressure, they are the cold set pressures needed to generate the higher 'hot' pressures that these cars need for fast use. That hot pressure can be several psi higher than the 'cold' set pressure.
Using nitrogen as supplied by many tyre monkey outlets these days is also bad. This nitrogen is dry and the combination of nitrogen coefficient of expansion and lack of liquid means that the pressure will not increase with heat as much as it would with air. The important pressures aren't the book pressure, they are the hot pressure that those cold set pressures were calculated to provide.
Edited by tvrbob on Friday 8th February 07:46
I'm interested to hear everyone's views as there is considerable variation in opinion. I run @ 22F and 24R on Dunlop SP9000's - but I always check cold dry tyres in my garage for consistency.
SpudMurphy said:
All true but my understanding is that car handbook tyre pressures all reference 'cold' tyres - to check 'hot' tyres is way too variable. Do you check after a 100 mile fast motorway trip, after hooning around back roads for half hour or after a short trip down the road to buy a newspaper? All are likely to give you pressures that will easily differ by up to 10psi.
I'm interested to hear everyone's views as there is considerable variation in opinion. I run @ 22F and 24R on Dunlop SP9000's - but I always check cold dry tyres in my garage for consistency.
I'm not suggesting we test tyres pressures hot. I'm simply stating that it is the hot pressure that matters, hence my comment about the stupidity of using dry gas. I did once test pressures on a trackday just to understand the issue better. I measured pressure increases of up to 6psi higher from cold to hot. I'm interested to hear everyone's views as there is considerable variation in opinion. I run @ 22F and 24R on Dunlop SP9000's - but I always check cold dry tyres in my garage for consistency.
22F and 24R on Dunlop SP9000's sounds low, that said I've never used SP9000's
Edited by tvrbob on Friday 8th February 12:15
LordGrover said:
What is the best method of checking tyre pressures anyway? I understand those gauges at the air pump on garage forecourts are not required to be calibrated regularly and may be inaccurate.
Those pen gauges that eject their innards are supposed to be very accurate and repeatable; personally I don't trust them. I use a 1.5" bourdon tube gauge range 0 - 60psi so that the required pressure is indicated in the mid range.The thing is that different tyres need different pressures. 22/24 was fine for S02 PPs but is crap for Goodyear eagle GSD3s which I found gave even wear at 23.5/26.
When I buy a new set of types I run them for a few heat cycles and a couple of hundred miles then use a marker to put a couple of stripes across the tyre with the tyre pressure a bit low. Go for a half mile blatt and look at the stripe. If it has all disappeared the pressure may bet right but give it a psi higher and go again. When you see the stripe on the outside but not in the middle lower the pressure by about 1.5-2 psi. That always seems to give me even tyre wear and good grip. If the stripe disappears on one side but not the other there may be a tracking issue. A pain in the backside maybe but it is a good excuse to give the car a good workout !
[edit] I use a pen type gauge and they are consistent - I don't know or care about accuracy as long I get the same reading again and again[/edit]
When I buy a new set of types I run them for a few heat cycles and a couple of hundred miles then use a marker to put a couple of stripes across the tyre with the tyre pressure a bit low. Go for a half mile blatt and look at the stripe. If it has all disappeared the pressure may bet right but give it a psi higher and go again. When you see the stripe on the outside but not in the middle lower the pressure by about 1.5-2 psi. That always seems to give me even tyre wear and good grip. If the stripe disappears on one side but not the other there may be a tracking issue. A pain in the backside maybe but it is a good excuse to give the car a good workout !
[edit] I use a pen type gauge and they are consistent - I don't know or care about accuracy as long I get the same reading again and again[/edit]
Edited by Bob the Planner on Friday 8th February 19:04
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