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julie09

Tyre pressure

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2 minutes ago, RogerH said:

That seems a little high for a standard car. My 4A is about 24/26 rear  26/28 front

 

Roger

Are they near side and off side pressures Roger :ph34r:

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1 minute ago, RogerH said:

...just an uncalibrated cheapo gauge...

I’m with you roger for the road I have my sprint classics at f26 r28

when I do sprints  with my vredestiens I do the opposite. As I try and optimise grip off the line with the rears and reduce tyre roll in corners at the front.

 

 

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Roger has his rear tires at a lower pressure than the fronts or has them both at the same pressure depending on how you decipher his tire pressures.

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Hi Stan,

                I've gone on a political answer. It is whatever best suits the question.

I used to go for 28 all round.  But I now have the rear end a little softer.

 

Roger

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That advice of 30/34 is absurd - even dangerous! (I know I am putting head on block!)

Start with 24 psi at front and 26 at back and then experiment and adjust

 

james

Edited by james christie

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Hi James,

I've always gone for either the same at the back or a little softer.

Working on the theory that the lower pressure gives a bigger foot print and thus less tendency to slip away.

 

If you replace just two tyres where do you fit them - on  the back, better grip.

 

Roger.

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Hah! But with all that weight up front don't you get too much understeer?

My tyres (Vredestein Classic Sprint) die of age so I change all four corners in one go

james

Edited by james christie

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My Godson aquired a TR2 that had the full monty restoration at a well

known south-west TR establishment.As it hadn't been used for some time,

I got to give it a full once over and thought to give said TR chaps a ring regarding tyre pressures.

30 psi all round is where we start said they.

So thats what is gets.

Roger M-E

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Tr4 & TR4A 22/24 front & 24/26 rear is what I generally use whatever the tyres.

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11 hours ago, Hamish said:

. I’m with you roger for the road I have my sprint classics at f26 r28

when I do sprints  with my vredestiens I do the opposite. As I try and optimise grip off the line with the rears and reduce tyre roll in corners at the front.

 

 

Hamish,

Sprinting you are about 10 lbs short, your tyres are in danger of rolling off the rims and you are loosing traction by allowing the carcass to deform and decreasing the footprint which increases the slip (not skid) angles on the tyres which reduces the grip. On road section tyres I've used up to 40 lbs and checked it with tyre temps to make sure they are equal across the width, no rolling of section.  

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4 hours ago, RogerH said:

Hi James,

I've always gone for either the same at the back or a little softer.

Working on the theory that the lower pressure gives a bigger foot print and thus less tendency to slip away.

 

If you replace just two tyres where do you fit them - on  the back, better grip.

 

Roger.

Contrary thought process works Roger, as posted on Hamish's post,

"you are loosing traction by allowing the carcass to deform and decreasing the footprint which increases the slip (not skid) angles on the tyres which reduces the grip."

Even on road use on a TR4 the front tyres need to be harder than rear, helps reduce the front end roll (even with anti roll bar) and stops the tyres deforming and increasing slip angles loosing grip. 28 front 26 (or 24) rear. Tr4a with it being an IRS car opposite apply 26 front 28 rear, however driving styles and preferences snooker all technical info, if you like it as is...drive it.

Mick Richards

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Thanks Mick :D

at Mira I kept putting the pressures up to try and get a confident feel.

i have moved to 55 profile maxsport soft compound tyres. These also have the benefits of a very firm side wall that have helped the handling in sprints a lot.  There is also a confidence factor in there somewhere. Together with an effective gearing change.

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Sprinting is an excellent introduction into motorsport.

It teaches the driver pace and lines where he can work it out whilst driving and not have the distraction of cars around him or overtaking.

It also allows the necessary exceeding of grip and consequential manoeuvres consistent with regaining control. Amongst these skills is finding the limit of adhesion numerous times, allowing the feeling of being "on the edge" to be logged by the driver in his memory. I fear the 55 section tyres will give you excellent grip until they go, but your reactions will have to be lightening quick whereas a 70 or 80 profile offers much more progressive breakaway and a chance to be caught by a new driver to competition. Remember...if your car corners like it is on rails...you are not driving fast enough.

 

Mick Richards    

Fangio drifting.png

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Mick you are right of course. But sprinting doesn’t give you much track time to learn the feel or settings, you have to have it right out of the box.

my castle Combe track day in the wet last year was brilliant tho.

but I was lucky enough to have been brought up around old cars and picked up a lot from my dad without knowing it, and in the ‘90s with driving older cars, my mistake was to beat him at Colerne in the same car!

But the best training I think is a lifetime on bikes. 

Being a petrol head I think they call it. the perm was ok in period honest !!!

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2F55BC16-89C5-4DE4-8070-95751F3EAFC4.jpeg

5E239FFC-A3A5-4C30-A7A9-7AEDB448BE0B.jpeg

05551087-BD6C-4DD6-96B8-F1C86EBF3BD3.jpeg

Edited by Hamish
Apologies for the hijack

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Cor...never mind being Hamish, just call him Harpo ! lol.

Practice days are better value Hamish, I used to use Mallory Park a couple of times a season running at 90% pace and altering the car settings and cross checking tyre temps to see what was going on at tarmac level. Then a couple of banzai laps to see what happened to the lap times and car feel and the most outstanding truism was if the car felt nicer...it was slower. Less understeer and the car turning into corners nicer...slower, altering the toe in more towards parallel from about 1/16th toe in...slower.

To return to the thread the tyre pressures on the road should be altered accordingly to your driving taste, although if you stray too far from what the worthies at various tyre firms suggest, if involved in an accident and a forensic test picks it up you are likely to be accused of contributing to it even though your tyre pressures may be delivering superior traction and grip.     

Mick Richards

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Thanks for all the input. Did not intended to start a war of words. Will go down to 26/28 and see if that stops the lightness on the steering when hitting 80mph.

thanks

ian

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Ian

no war here so don’t worry. Sometimes we can go off on a small tangent but it’s all good fun.

play about with your pressures to see what suits. But if it’s higher speed stability check to see what “toe-in” you have. 

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