strong

I believe that I treat my S-02s pretty hard and consequently don't get more than 10k miles out of them, so I'm looking for advice on tyre pressures, tyres and even driving style in an attempt to minimise their wear while on the road and on any track days I may do in the future.

On my UK 98MY Scooby I've recently been playing with tyre pressures and found that with my usual 34 psi front / 31 psi rear settings I get excellent grip but on my favourite roundabouts and corners it doesn't take a great deal of commitment for the tyres to sqeal. However when I ran 36 psi all round I didn't get any squeal at the limit, just less grip than before. (This is all on dry roads of course.) Wet grip was greatly reduced at this pressure however.

I remember someone once telling me that tyres squeal because they are overheating. Could someone explain this further, and what can be done about it?

The biggest problem with the S-02s, as others have found, is they wear their shoulders quicker than the central tread area. I guess this is down to their more flexible sidewalls compared to other tyres.

Obviously a harder compound tyre would last longer, but the S-02s have a treadwear rating of 180 while another good tyre such as the Goodyear Eagle F1 has a rating of 200 (according to their US website at least). I can't imagine a small rating difference like this giving me many more miles. And Mike Nunan has commented to me that his F1s also have some of the S-02s squidgy sidewall attributes, so I wouldn't expect their sidewalls to fare much better than the S-02s.

Another tyre doing the rounds amongst the owners here is the Toyo T1(-S?) Proxes. Can anyone tell me their treadwear rating? Also comments on grip/longevity on 16" wheels would be useful.

I'm not just looking for tyre recommendations though. Is there some magic driving trick to make tyres last longer? I don't throw the car into corners at high speed and drift all 4 wheels. No tyre-******** exploits like that at all. However I don't employ the slow-in fast-out method either. I use a good entry speed, power on early and use all the grip available.

Part of the problem is that most of my driving is to and from work just outside normal rush-hours, where I know the corners intimately and consequently enjoy them all the more.

Paul

AlexM

Paul,

What suspension do you have fitted, and what geometry settings are you running?. These will probably have a greater bearing on the amount of tyre wear than pressures, unless you're grossly underinflating/overinflating. I am running 33 front / 31 rear, and have found the handling and grip to be good with these pressures.

Excessive toe is bad news for tyre wear - have yours checked and adjusted. Increasing your negative camber should also help reduce the wear on the outside edge of the tyre, but it obviously increases wear on the inside edge.

When I had my S02's fitted recently, Toe was slightly out of limits at the front, but I have slight POSITIVE camber on the front left - Ooops must get that sorted out....

Rgds,

Alex

Yex

Strong,

If it's any help to you I drive a MY98 with the standard suspension and OE10 tyres fitted from new. I have had my suspension geometry changed to the recommended Pro-Drive settings and the difference is a much better feeling car. My previous settings were quite a bit out and this would probably explain why the car felt different after the adjustments were made.

I run 33 psi front and 31 psi rear and this is checked every weekend prior to serious use At the last service the tyre readings were 5mm all over on all 4 tyres. This is after 17,000 miles of enjoyable driving and two fairly heavy track days, so I am pleased with the way the tyres have held up.

If you do a search on the subject of geometry settings you will find plenty of info, and the FAQ area of the SIDC website has the necessary Pro-Drive settings if you want to go down that route.

Regards

Yex

Stef

On a similar note, Paul Gander from EVO mag reckons he's used his TOYO's for 15,000 miles including 10 track days!!!
Read from that what you will.

Stef.

Stuart Knight

iTrader: (2)

I highly rate the Toys. At MIRA on Saturday the grip was superb, and when they let go they let go gradually. I find it hard to believe anybody could get 10 track days from them unless they don't use the brakes or throttle. I used mine at Donnington and they got very hot and sticky in about two laps and then started to disappear! The standard RE010 are excellent on the track though, they get hot and sticky but don't disappear.

strong

I have standard suspension and changed to Prodrive geometry settings about 4 or 5 weeks ago. Before that I had the settings checked last March along with my first set of S-02s and had it corrected to Subaru standard (factory settings were way out).

I guess I haven't had a chance to see the effects of the changed settings on tyre wear, so in a few weeks when I change my tyres I might still go for my third set of S-02s. The Toyos are quite a bit cheaper and might be worth a try and then ******** them on a track day isn't so bad. Sounds like Gander drives like a wuss on track days ;-)

Paul

KRIS

I have totally ( ish ) std uk 98. I run 36 psi all round and have done for some time. The tyres have hardly worn at all and the grip is no difference from before. The ride is ever so slightly harder but soon forgotten about.

The police impreza`s in Humberside run 36 all round and they have greatly reduced their tyres bill. On track days I would increase these to 40 psi all round to give much greater tyre wall stiffness. Had no probs at the recent Donnington track day.
K

strong

Good point about track day tyre pressures Kris. It was something I meant to bring up. BTW, what tyres are you running on Kris?

I've checked my tyre pressures immediately after hard A-road driving and separately after a high speed motorway run and they were all about 42 psi compared to the 36 psi all round I was running when cold. On a track day the tyres will get to this also.

Is there any reason not to run at 40 or 42 psi on the track to help preserve the tyres' shoulders? I'd guess that as long as the pressure when hot doesn't exceed the tyre's maximum permitted pressure then this should be OK.

BTW, phoned Micheldever Tyres today: 16" S-02s are currently £106 all inc. They don't do Toyos. P-Zeroes are the same price but RE010s are £110!

With the comments about RE010s being alright on the track, it's tempting to get a set of old wheels with this tyre for the track. I'm not interested in slicks -- my idea of a "track day" is a few days at the Ring.

Paul

[This message has been edited by strong (edited 13-03-2000).]

Stuart Knight

iTrader: (2)

I set my tyre pressure to 36psi cold at Donnington, went out and did about 5-6 laps anf the pressure went up to 45-46 psi. Way too hard, so we dropped the now hot pressure back to 35, went out again, and again the tyres went up, (but only the lefts (right handed circuit)) to 45psi. Dropped these back down to 35 psi again, and the tyres did about another 70 laps with no appreciable wear (there must be some, but they still have a good 5mm left on them) These tyres did half a day at Donnington in November, and have been used on the road for about 3000 miles as well, from new.

MorayMackenzie

KRIS and others,

Increasing your tyre pressure will decrease your tyres contact patch, therefore decreasing your car's grip.

When I have experimented with tyre pressures I have always found that the car looses grip and becomes more 'edgy' as I increase the pressure.

If I wanted to play with oversteer at modest speeds in the wet I would leave the front pressures alone and up the rears by several psi. I would also make a point of returning to standard safe pressures before leaving the carpark.

Moray

Stef

If you intend to drive hard at track days I had some recent advice saying that it was far better to use part-worn tyres than fairly new road tyres, as the tread isn't as deep and therefore doesn't get as hot (something to do with deep tread giving more movement).
Dunno how accurate this is, but it seems to work for me.

Stef.

Tony Quinn

I ran RE10s at the recent Donington day. 36psi cold at the front, 33 at the rear per Scoobytrax recommendations. The front tyres went from 5mm to destroyed, the rears from 5mm to 3mm. Wear on the fronts was of course worst on the outer shoulders, but there was also alot of wear in the centre (with tread in between thes two areas. I reckon on using no more than 32psi on the fronts next time, and adjusting the rear pressures to tune the balance of the car as Moray suggests.

Having intimated that the RE10s can disappear very quickly on track, they had survived a trip to the 'ring. I guess that I must have been driving like a wuss though. I did notice that there were quite a few cars at Donington that had considerably more grip than my car. How much of this was down to suspension mods and how much was down to the ubiquitous SO2s, I can't say.

Paul, how do your tyres cope with a few days at the 'ring? and how hard do you push there?
You might consider Falken FK451s, I have no opinion myself but I have read a German magazine article which rated them very highly. I think that the treadwear rating may be 280 and Micheldever sell them for about £75.

I've heard the same comment on treadblocks as Stef. This makes sense to me. I went to Silverstone with some nearly new Yoko 520s and left with slicks, despite only doing about 20 miles at speed. The rubber had quite clearly melted and had been scrubbed away very quickly.

strong

Tony,

At the Ring I've only been learning the circuit, so to preserve tyres I've taken it easy for most of the time. However I did particularly notice that the outer shoulder of my rear right tyre took a real hammering. The rears had been on the front for 6k so the shoulders were shabby to start (and the right tyre seems to fare worse than the left on the front) but within 8 laps there was no tread for at least an inch in towards the centre of the tyre on the right rear. This was running 36psi all round, and gave me 42psi after a lap.

I think anything with a 280 treadwear rating should be on a set of 'track day only' wheels. I wouldn't like to experience those in the wet on a UK B-road (having had 300 rating Continentals on the car when I got it). Thanks for the tip though, the more the merrier.

Paul

[This message has been edited by strong (edited 15-03-2000).]

Lars

To Moray, sorry to say but what your write is againt all normal tyre pressure teori I have learned. I normally do classic car racing, and have been doing racing for around 20 years in different cars.
If you go track racing on dry surface,using road legal tyres, all racing drivers I know ingrease the pressure up to a max of around 40 PSI ( cold )
It is normal to play with the preasure to adjust the over / under steering. If your start out with 38 all over, and feel that your car oversteer, then try to lower the pressure in the back this will give less grip in the back. try lowering with 2 PSI at a time.
Higher pressure give more grip and less wear on the shoulders.
I use 38/32 last time i did some track racing with the Impreza.

Less tread surface with higher pressure is something you had in the 1960 before radial tyres where available.

If you use racing tyres, forget the above they react nearly opposite a road legal tyre.
In rain you normally use lower pressure.

Road use: If your check the ideal pressure for a given tyre ( from the tyre manufactor) it will normally be higher than the pressure the car manufactur suggest. The reason for this is comfort.
2PSI higher than the car manufactor suggest for normal use is normally the best for the wear and for the grip.
The above is general and not specific for the Impreza.

Lars

strong

Lars,

People today are still told that if they overinflate their car's tyres they will have increased wear in the centre -- ie the contact patch is reduced to a more central portion. This means you have less grip.

You believe that this only applies to cross ply tyres (quote:"something you had in the 1960 before radial tyres")? If so, could you explain why.

Thanks,
Paul

Bob Rawle

I have ALK fitted. Once fitted you will need to get your alignement set up again as it will screw up the settings. I ran with 1.5 neg camber and 1.0mm total toe on the front with 1.1 deg negative and 1.0mm total toe on rears for 18500 miles using SO2's on 16's. Tyre wear even across the piece but I do swap fronts to rears every 3500 miles. Then finished them off at Donno. Having the geometry reset tomorrow at Micheldever so will report findings.

Tyre pressures ... I run 3 psi more on the front than the rear and adjust this differential and pressure level until I get best feel. SO2's ran 33/31 front and rear, now using latest Falken tyre(good as the SO2's IMHO)but needed 34/30 to get same result with ALK. I always increase to 38/36 for the track to stiffen up side walls and reduce heat build up. Running same pressure all round makes my car understeer.

ALK provides much better " bite" through corners and is well worth the money with standard suspension but does not seem to work as well with Leda for example.

Bob

AndyMc

I have also been wondering why the outside of the front tyres wear so badly.I have a my 98 fitted with an ALK.The S02's on the front have only done 4k miles and the outsides are f**ked already.I got 11k out of the originals (swopped at 7k)

I used to get 18k miles out of a set on my Corrado VR6 with even wear across the tyre despite the fronts having 190 bhp running through them.The Corrado also leaned more in corners

Andy

Lars

Strong, I try to pass on the explanation, it is originally from a Pirelli tyre engineer.
Todays radial tyres are build with steel wire, carbon and other strong material. The tread is build up of several layers in a way that prohibit the tread to change even with very high pressure. High pressure will only stiffen the side walls.
The engenier showed several excamples on recomended Pirelli pressure compared to the pressure recomended by the car manufactor and Pirelli always recomended a higher pressure.

My English is not the best, but please read the comments from Bob Rawle I fully support him. 36/36 will make every Impreza understeer, even with Pro setting.

I have always been told that more than 40 PSI will not give any effect. But I do not know the reason.

Make a test using same corner or a roundabout, neutral power start out with same pressure front back, don't care about the speed just find out if your car under or ower steer, when you go round and round increasing the speed slowly. Then lower the pressure in the back and feel the different. Less pressure = less grip.

As most of us do not by the Impreza to get high comfort, the redused ride comfort with 2-3 PSI more than standard is the best both for the grip and the wear.
Your will also reduce the rolling resistance a bit and improve the top speed.
People doing economic race ( Go for lowest gasolin usages) use normally 40/40 or even more. They don't care about comfort or grip.
Lars

strong

Lars,

Thanks for taking the time to explain that. It's much appreciated. It certainly explains why Scoobies handle best on 33 or 34 psi front and 31 rear -- a few psi more than Subaru's recommendation.

Paul

PhilBennett

The people who told you guys to run 36psi front pressures at Donington were having a laugh. When hot that went up to over 42psi.

Now given these things understeer anyway - it just made it MUCH worse.

At the end of the day if your getting over 10K miles out of a tyre on a 200+bhp car driven fairly hard with the odd track day thrown in - I'd be quite happy.

Regards the tyres you are using - if you go for performance tyres with treadwear ratings of 180-200 what can you expect. Get some caravan tyres rated over 400 or simply drive slower!!

Gethin

Bob,

I'm running new Falkens too. They are just as good as anything else i've used. Also they have a lip on them that seem to protect the alloys from small kerbs....

...and I got them for £75 each !!!!


Gethin.

strong

Gethin/Bob,

Can you tell me the exact model of these Falken tyres? If you also have the treadwear rating then that would be very useful too.

Paul

Bob Rawle

Paul, They are FK451 Falken Ultra Premium, cost £70.20 per fitted and balanced from Micheldever.

Treadwear 280 !!
Traction AA !!
Temperature A !!

So as good as the SO2's but more hard wearing and definately stiffer side walls.

So far I have covered 4,200 miles and "lost" 1.5 mm tread ... bearing in mind the torque I have (and use) that's not bad.

SO2's did 18,500 on my car ... I expect these to be just as good if not better for wear rate.

They are a Japanese made tyre.

BTW Phil the 18,500 included one Castle Combe track day (my "home" cct ... 90 laps during the day) and the November Donno track day. I agree your comments re track pressures except that I have found that you need far more pressure in road tyres than slicks ... from 38/36 my tyres end up at about 42/40 which suits my car down to the ground, slicks would be another matter though and I have yet to experience them so I will welcome the advice as and when I do..

Bob

[This message has been edited by Bob Rawle (edited 17-03-2000).]

strong

Blimey! Traction AA *AND* treadwear 280. I thought those sort of ratings were mutually exclusive. And at that price I don't mind so much if they turn out to be a bit naff.

I always like a second opinion so, Gethin, what were your previous tyres that you're comparing the Falkens with? And to gauge you're driving style, how long did your previous set(s) last?

Thanks,
Paul

KRIS

I think the topic is being split up now into a couple of things :

1. track day pressures on non road tyres
2. track day pressures on road tyres you want to preserve as best as possible
3. slicks for track use only
4. Normal road tyres for normal use
5. grip available in all the above

IMHO... To summarise....Road tyres , no matter what sort will get a right good hiding if used on the track. Lower pressures on road driving will obviously increase grip however, do you really reach this limit on the road ? Therefore the original question stands and the answer is a grip / ride quality / contact patch and mileage trade off.
I still think that if you over inflate a radial that you will still `BULGE` the center of the tread section. This will be minimal. At Donnongton I was running standard potenza`s but at 40 psi( cold ), the shoulder of the tyre still got the wear rather than the center of the tread section.
Still as its a trade off you may as well carry a foot pump and pressure gauge and be constantly chaging them when you drive 1.on the motorway
2.slippery wet country lanes
3.bone dry summer A roads
4. and finally on the track.

As i said earlier my pressures are 36 all round and I`ve had no worries with grip or wear.
K

Bob Rawle

Paul, double checked in the daylight and its definately Traction 280 etc.

Kris, 36 all round on 15 or 16 inch rims and what tyres ?

Bob

strong

When I enter a corner on the track and the tyres start squealing is that simply telling me that I'm entering too fast and the tyres are being ripped up or should the tyre pressures be altered in some way?

DocJock

Bob

What are your Falkens like in the wet compared to SO2s ?

I had some of the previous type and they were great in the dry but absolute pants when it rained

Regards John

johnfelstead

not read this thread before, here's my pennies worth.

For the road always set your tyre pressures when COLD, you will get consistent setting then, even a couple of gentle road miles is enough to up the pressures.

I have found 32 front 30 rear cold works best on my sport on 16" wheels.

For the track you must set your tyre pressures when HOT, you will get masively different presures on each wheel after a couple of fast laps of a race track, the front outside tyre is allways higher than the rest.

Set your pressurres at 36PSI front 34PSI rear when HOT, check it after every run and adjust untill it stabalises. Check and set the presures AFTER your fast run and you have just come into the pits, not just before you go out.

The ideal road car tyres for the track are ones with very little tread depth, as the deeper the block the more heat is generated.
To give you a good illustration of this, this story comes from the dunlop engineers that developed slick racing tyres for sports car racing (they were used in sports cars before F1, contrary to the popular belief).

They were testing the new slicks on a big capacity sports car and the rubber surface was overheating, so they had the bright idea of cutting a few grooves in the surface of the slicks to cool the surface down. The car went out again only to come back in after one lap with the driver scared to death
They inspected the tyres and the surface of the slick had literally melted into a mush

They then sussed out what had happened. The grooves they had cut in the slick had allowed the surface of the rubber to move around and instead of cooling the tyre it had actually increased the heat generated masively and melted the rubber.

bet you didn't know this either, rubber tyres are not a solid, they are a very slow moving liquid and the more you heat them, the more the liquid flows, thats why you see they look like they have rolled over to one side on the tread block, that is not caused by rubbing, it is caused by the rubber flowing that way when it is very hot.

Bob Rawle

John, so far so good, I would say they are very comparable to the SO2's although, as the sidewalls are stiffer, they have a totaly different feel to the SO2's. Lets just say that I have no less confidence in the car on them compared to the S02's

Bob

[This message has been edited by Bob Rawle (edited 19-03-2000).]