Track Day Tyre Pressure

[burrellbloke]

I had two excellent track days at Croft and Donington recently. I took my track wheels which were a set of 17" Oz Ultraleggeras which had part work Direzza DZ03Gs on them. The tyres are 215 45 R17. The tyres had about 3 to 4mm on each tyre. I don't know what usage the tyres had had before I got them but they seemed to have fairly even wear across the tyres. I picked them up for a bargain £200.

Croft has a lot of right hand turns, as does Donington.

After finishing Croft the front passenger tyre had worn considerably on the shoulder of the tyre and it had sorted to delaminate. I originally put that down to aggressive driving, a bit of kerb smashing, and the car having a mild Gripper that was putting new strains on the tyres that had not been there before.

For Donington we swapped the wheel from the front passenger side to the rear passenger side. At the end of the day at Donington we had the same wear/damage to the front passenger tyre. Donington involved a lot of right turns and a lot of kerb smashing.

I have not really kept an eye on tyre pressures, but when they have been checked the pressure is usually about 30 hot. Should I be running the tyres at a higher pressure so that they have a stiffer tyre wall? Would that slow down the wear on the outside edge/shoulder of the tyre.

Also, the car is usually quite heavy as it has @EthanMenace and me in the car at track days. Does the extra weight need to be accounted for with tyre pressures - if so should it be higher or lower?

 

[RSRowe]

You can try higher pressures, but i imagine you'll start to wear the middle of the tyre then.

Altering the geometry can help, but ultimately most tracks are clockwise and if you're pushing on, you're going to wear the front left.
The direzzas are soft, don't last long, and were pretty much done when you bought them really. Obviously you boys are car sharing, so you're always going to be going through tyres twice as fast.


On my car, it's only now I'm running 3 degrees of camber and hard compound MRF's that I have got on top of tyre wear.

 

[Big Ben]

30 hot seems about right. I had Direzza and as good as they are I’d not get them again at the prices. Nankang AR1 are not directional so you can swap sides to keep the wear even. I rate them highly for the money you can get them new

 

[LiamP]

Bump your rear dampers / pressures and get the rear moving instead, that will quickly solve any wear on NS front!

 

[LiamP]

@NickD mentions rotating the tyre on this thread do the Dunlop’s have an outside/inside?

 

[burrellbloke]

@NickD mentions rotating the tyre on this thread do the Dunlop’s have an outside/inside?

I am fairly sure they have - I will have a look and check.

 

[Helpimonfire]

I'd say the Direzza won't have a labelled inside/outside as it's a directional tyre. My Kuhmo V70's are directional and they don't have an in/outside sidewall.

 

[NickD]

Firstly, tyres wear. It is the way it is. Dunlop is a very good tyre, the complaint always is "the shoulder has gone."
I weighed my "standard" car at Donington, it weighed 1,250kg. I would look to run 34 to look after that. Tyres wear though. You can do 3+ hours on a track day. I wouldn't expect any tyre that is being "used" to last longer than that.
Listen to the tyre squeal in this. That is tyre wear right there.

 

[bedoef]

Its a combo of tire pressure camber and setup - unfortunately there is no real fast fix. You will have to play with each of these one at a time to figure out how to get the most even wear on the tires.

For pressures, first see what the manufacturer recommends for hot temps. AR1s run better around 27 hot, the Kumhos I have on the Clio now prefer 32-33 hot. If you have a IR thermometer, you can get an approximate reading across the face of the tire, and play with the pressure until you get them as close to even across the tire as you can.

Also check the wear indicator mark on the sidewall. If you are wearing past that, you are probably under-inflated for the tire.

 

[strell]

One of the best things I got for checking tyre wear is a IR thermometer gun.
Helps you see where the heat is.

If it’s all on the inside you are either running too much camber or not pushing hard enough.
If it’s all in the middle you have too high a pressure
If it’s all in the outside you need more camber.

Obvs that’s not the only factor as toe does come into place.

But I’d say if you are wearing the outside edge really quickly adding more camber should definitely help.

 

[LiamP]

As above once you have fixed any obvious geo problems but getting perfect wear != quickest setup.

 

[burrellbloke]

Thank you for everyone's comments.

The Direzzas have got a directional tread.

I was expecting the tyres to wear faster with a Gripper and a more aggressive suspension set up. Alex at AW Motorworks set the geo up with a mild track/fast road set up for the car to carry a passenger. The front drivers side is -2.5 degrees and the front passenger side is -3 degrees. I was just curious to see if a different approach with tyre pressures could help slow down the tyre shoulder wear rate.

I will run the tyres at 34 hot and see if that helps at the next track day.

I might invest in a set of MRFs when I have got through my current tyres if I am able to rotate the wheels from both front to back and side to side.

 

[John Gordon]

What are peoples starting pressures? (Cold).

On my last track sessions a few weeks ago I went for 31/28 (R888r). Forgot to bring a pressure gauge with me so was just winging it.

Felt like I could come down a bit at the front as I had a bit of understeer. Curious where others start from?

 

[RSRowe]

Usually 24f 26r gets me where I need to be.

 

[strell]

I usually head out about 27 and then drop it some more when it gets to 31 or so and try to get it to settle about 30 hot with most of my track tyres

 

[burrellbloke]

In the official 197 supplement book that came with the car, they state tyre pressure - 'For Motorway only' is 35psi front & rear. - cold.

I expect in Renault speak - 'Motorway Only' means track use !

I would personally not reduce pressure from a hot or warm tyre.

I cannot work out if your are trying to bait someone in to responding to you.

 

[R20BTG]

I expect in Renault speak - 'Motorway Only' means track use !

Whereas I suspect it doesn't.

 

[RSRowe]

I would personally not reduce pressure from a hot or warm tyre.

For what reason?

 

[burrellbloke]

Just do what you feel is best. - I saw your original post, and thought i'd offer another opinion for you.

I agree that it is all very subjective. For the past few track days 31 psi hot has been the sweet spot for the Direzzas that I had been running to avoid too much ear on the shoulder, and to maintain excellent grip on track.

 

[John Gordon]

Never had to - or felt like doing. It's a very subjective matter, and all I can really go off is the official Renault book - which for continuous fast driving states those 35 psi pressures when cold. My car is completely unmodified and standard, - so i'm happy with those numbers.

FWIW - letting pressure out for me when hot, will allow considerable sidewall flexion, and rolling towards the edge of the rim. Also once pitted and cool again, the resulting lower pressure will allow a lot of sidewall distortion until up to temperature. (I have also read that you shouldn't deflate a hot tyre to reach recommended pressures)

I've had a fair few quick cars on track in the past, - and it's just my way. - I see people measuring temps etc in the pits, which is fine for them.
It's a real black art - and like I said - happy to go by the Renault book for my standard setup.

Just do what you feel is best. - I saw your original post, and thought i'd offer another opinion for you.

Have you tried using Nitrogen instead of air? - as it doesnt have the same expansion properties across the tyre temp range.

Driving continuously "fast" on a motorway won't produce anywhere near the temperature that high load cornering forces will generate whilst driving on track. Then there's the brake temperature which increases the core temps significantly.

Besides, if I remember correctly the official Renault pressures for the road are 33 psi front and 30 rear/ 33 rear for heavy loads.