Peter Horlock

IN a week or two i'm off to a track day with my WRX. Now i expect to trash the front tyres (at croft), but not the back. But for the subaru if i change the two fronts ( as the edges will most probably be worn out) do i "have" to change the rears as well. I am putting on the same tyres (TOYO's). Any advice from people would be most greatful.
Yours

peter
p.s its a green WRx bugeye wagon if anybodys off to the RS track day say hello.

steve_g

I did a track day at Donington on 13th and I was worried about trashing my tyres. I'd say over the 200 miles I did on track that I lost about 1mm of tread.

I wouldn't worry too much about excessive tyre wear. Up the pressures a bit to reduce the wear on the outer shoulder.

Redkop

I did track at the RS day last year at Croft and it wasn't hard on the tyres

Edcase

Hi Peter

you can also do what I used to do and rotate the fronts and rears during the day to keep the wear even.

Make sure you use a much higher tyre pressure on the day, particularly the fronts!!! It depends on the track but I wouldnt go less than 38-40 on the fronts and sometimes a lot more. Croft is one of the few I haven't done so cant help I'm afraid.

Just dont forget to let them down again before driving home!!!!

Gutmann pug

Higher tyre pressure on the track ...........why???? ........ The tyre pressure will automatically raise due to the very high temps they will be running at on the track wont they? surely this will mean that they raise even more and will end up like ballons? It may save your tyre wear a bit but i qwould rather have worn tyres then end up in the armco?

I may be proved wrong on that but thats how i thought it worked? ....... lower tyre pressures for the track, then once they get hot they will be at normal (ish) pressures?

billythekid

I would seriously advise against running any higher than normal pressure.

If anything you might want to lower the pressure at cold.

I look for tenths when on track so tyre pressure can be very critical, but if you are just out for fun run road pressures and then keep an eye on the pressure (take a reading before and right after each session).

billythekid

BTW i have been known to run as low as 12psi in the wet on my car, admitidly 500kg race car

MikeWood

Raising the tyre pressures means that the tyre flexes less and doesn't overheat the edges leading to premature wear and potentially failure. Having said that, unless you are experienced on track and try to slide round every corner then that won't happen anyway. Whatever you do, don't be tempted to lower the pressures in response to them getting warmer and the pressure rising, that's exactly what they have been engineered to do.
This isn't about getting the last tenth of a second out of a car on the track, it's about being safe and making sure you can drive it home!!

Sprint Chief

Depends on the tyres you are using

"Proper" track tyres have very stiff sidewalls and don't need as much pressure.

Road tyres have soft sidewalls and at normal pressures just fold up under hard cornering.

My brother used to run stock hatch (750MC) with standard road tyres and increasing the tyre pressures such that they were at the maximum allowable pressure when hot would take about a second or so off the lap time!

Also the tyres would overheat very quickly at normal pressures (like 2 or 3 laps) and lose all grip (three seconds on the lap time...) whereas at 40-something PSI they would just about last the full 10 laps!

Sprint Chief

Or what Mike said

Posting overlap!

Edcase

but presumably you are using slicks / track tyres on your 500kg race car??

We are talking about a 1500kg saloon car on 45 profile road tyres. In tight bends on 'road' psi settings on track tarmac your tyrewall will just flex / fold under and you will understeer.

I would seriously advise against LOWERING tyre pressures from cold on a standard road car going on track

Edcase

Unless maybe if you run high pressures on the road and the track is very very wet...

Edcase

LOL, ditto!!!

billythekid

Exaclty - thats why I said to use road pressures.

I play with my pressures because I have a race car that runs slicks and to get the setup right makes a big difference, but on a road car its not going to make that much difference.

billythekid

I may be wrong, but it seems Peter is a novice to track days, so he wants to keep his car handling the same as he is used to.

My advice is, keep road pressures for the first session or 2, build your pace and monitor your pressures. Then if you are starting to build more speed then ask someone at the track, there should be a few ARDS instructors around and they will help you.

I have been around the track day scene for many years and been instructing for the last year or so, and novices don’t need to worry about things like set up, they need to concentrate on the racing line, building pace and importantly keeping a close watch on their mirrors.

Edcase

disagree completely, sorry. simply raising your front pressures by 5-10psi over road tyres on a dry track will do wonders for turn in and tyre longevity.

There is so much more room for movement on a road tyre, and then there is the extra weight, higher centre of gravity, more body roll etc etc.

Race cars have so much more grip inherent within the chassis that the tyres work so much harder, and so smalle tyre pressures can make a huge difference. With road cars on normal tyres you are simply stiffening the tyre wall to maintain the optimum contact patch.

Edcase

agree with that completely however

there is NO subsitute for pro tuition, regardless of how good you (think you) are.

billythekid

FFS I know that - I said "much difference", as he is going to be pootling around for the first few sessions if he has never been on a track day before.

The bottom line is he should consult the ARDS instructor on site on the day, job done.

Sprint Chief

[scouse]
eh, eh, calm down, calm down!
[/scouse]

Edcase

LOL, calm down mate.

The first thing an ARDS instructor ever told me when I first started doing trackdays was (in the typical northern sarcastic humour way) 'bloody hell mate you're not running standard pressures in the front are you'

Edcase

helps your cornering....

davyboy

I went to the ring last month in my 944 Turbo and after 2 laps the tyres were up to about 50psi, and it felt crap.

Reduced them to mid 30's and it felt as if I was using slicks the difference was that much.

I would personally sacrifice wear for grip.

njkmr

[QUOTE=davyboy]I went to the ring last month in my 944 Turbo , and it felt crap.



Get yourself a Scoob you nutter you!!!!!!!!!!!!!!!!!!!!!!!

Ha Ha Ha!!!!!!!!!!!!!!!!!!!!!

Gutmann pug

He had one,,,,,,,,,,, thats why he bought the porsche lol ......

njkmr

Well he should have got a proper porsche then,911 or something!!!

chris's scooby

I can't help feeling that we've all missed the original question which was if he changes the front side, will he need to change the rears as well?

davyboy

I might have had a "proper" one if Impreza's didn't devalue faster than a Lada!

.....wasn't that much faster than one either I seem to remember.

Dave

Edcase

Davyboy, that is because the ring is more like a fast road than a typical circuit. Much higher speeds for much longer etc etc.

I've never seen my tyres go up to 50psi and I've done almost every track in the UK.

T5NYW

iTrader: (4)

I agree and so going back to his orignal question

I assume that your concerned about just replacing 2 tyres instead of replacing ALL 4 tyres, which is to a degree the said "norm" on 4WD cars with fixed 50/50 diffs.

As the UK scoob centre is approx 60% front 40% rear the tyre wear is proportional and Tread wear will reflect that. Unless you change the wheels front to back regulary to keep wear rates even. I believe 4mm difference is accepitable IIRC. I have always fitted the newer tyres to the Rear.

Tony

Ps

On the tyre pressure front I have to agree with everone if your a good experienced Driver and unconcerned about tyre wear and "Lap times" is your game, yep lowering Pressure will indeed give better lap times. For us less experienced Drivers I agree in increasing tyre pressures to preserve tyres and give a better turn in and maybe a more predictable level of grip. IMHO

Edited to say best advice is "Your drove the car there , you would like to drive it home" take it carefull and repect the track it can bite you back otherwise

davyboy

What are std tyre preassure for an impreza?

It was a hot weekend, and I think 944's run a higher tyre pressure. I am not saying it will work for all cars, but certainly in my experience it works.

But with the 4WD tall and narrow tyres, it may be a different ball game.