Tyre Issues at Broadford

jayarr · January 22, 2018, 10:11:05 PM

Hi all,

had a ball at Broadford, great track, challenging turns and scenic surroundings. BUT, in the follow up found significant damage on the outside edge of the front left tyre. This was on two different cars, both FWD (Alfa Mito and Fiat Ritmo), with tyres that were relatively new.

Any other competitors face the same issue?

Many thanks.

John.

Neil Choi · January 22, 2018, 10:16:21 PM

Lack of negative camber and FWD. Perhaps.
Tyre type and pattern?

Neil Choi · January 22, 2018, 10:16:57 PM

Maybe it's the Bradford bats too.

jayarr · January 22, 2018, 10:41:39 PM

"Bradford" Post title corrected

Two different tyre manufacturers Michelin and Continental - I know - maybe that's the problem right there.
Standard camber.
No tyre issues with the Mito at other tracks.

Colin Edwards · January 23, 2018, 08:48:52 AM

Hello John,

What tyre pressures were you running? May have been a bit low given the outer edge scrubbing?
Corners 1/2 and 10/11 will be tough on the LHF. High wear due to overheating?

dominic.morello · January 23, 2018, 09:21:15 AM

John, I too had some pretty bad wear on outside of front tyres with the mito although not as bad as yours. Although I did only half the laps that you and Liam did

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jayarr · January 23, 2018, 10:02:09 AM

Quote from: Colin Edwards on January 23, 2018, 08:48:52 AM
What tyre pressures were you running? May have been a bit low given the outer edge scrubbing?
Corners 1/2 and 10/11 will be tough on the LHF. High wear due to overheating?

Tyre pressures around 37 PSI (hot) at the front, the same as run at other tracks.
The local tyre bloke reckons damage to the tyre is due overheating, rather than hitting kerbs or fenders rubbing.
When I checked again this morning, there is evidence of the same problem on the right front as well, though to a much lesser degree.

Suspects at the moment are:

Insufficient camber
Low tyre pressure
Tyres not up to temperature before hot laps
Continuing braking through the entry into the highly loaded corners

Unfortunately the last 2 items are behavioral changes, which are much harder to get right!

Colin Edwards · January 23, 2018, 11:27:28 AM

Hi John,

Although its not much of a comparison, but my son ran 43 cold / 48 hot in the (non r rated) fronts of my 75 3.0.
More often than not a tyre will run cooler at higher pressures.

alanm · January 23, 2018, 01:17:34 PM

innteresting given that the silver 156 was running road tyres which were given an absolute bollocking and I don't think they failed. Same hot conditions, the difference perhaps was the 156 has a lot less power. Disappointing failure though 😐
The Dunlop Direzza Z1s on our 75 proved their worth in difficult conditions.
I can definitely recommend Z1s/Z2s (road legal).
Al

jayarr · January 23, 2018, 07:35:41 PM

Quote from: dominic.morello on January 23, 2018, 09:21:15 AM
John, I too had some pretty bad wear on outside of front tyres with the mito although not as bad as yours. Although I did only half the laps that you and Liam did

Sent from my HTC 2PZC100 using Tapatalk

Thanks Dominic - sorry to hear that you had a similar issue.
I think I was braking harder into the corners, but you were getting better drive out of the corners. Maybe the braking contributed to overheating the tyres.

Evan Bottcher · January 23, 2018, 08:51:13 PM

It's been many years since I've run road tyres on our sud car, but I have a very strong recollection of disintegrating a set of bridgestone road tyres in exactly the same way on a hot day at Winton. They got too hot, melted and blistered at the edges like yours have.

My guess (no really a guess) is that you might have done a little better with higher pressures. Several people have told me that heat build-up in road tyres is majorly affected by sidewall movement - road tyres have thin and compliant sidewalls for comfort. Higher pressures will reduce the amount of sidewall flex, at the cost of overall grip perhaps.

Sheldon and I ran our shiny (not) new 156 Twin Spark on the set of mismatched road tyres it came on, a mix of pirelli, continental, and some chinese brand. We ran them at 42F/40R hot, they howled like crazy but didn't blister.

Sportscar Nut · January 23, 2018, 09:41:39 PM

John, completely agree with Evan's comments. The 'flat' edge on the tyre looks like you have punished them but too much movement.

Ya might need a spare set of more suited track tyres for the Mito. Hope your well.

Paul

Colin Edwards · January 24, 2018, 10:34:05 AM

Hi John,

Powerflex in Huntingdale do poly bushes for the Mito front lower control arm.
The stiffer polyurethane will reduce the loss of caster and reduce the increase in positive camber during "spirited" driving. End result should be less wear on the outer edges of the tires. The front wheels will effectively remain a bit more upright during cornering. This will put more of the tyre on the road and reduce understeer a bit. Tyre will run a bit cooler as the heat is not as localized. Still will need to run tyres at around 40+ psi cold though. Just a thought!
Also wouldn't hurt to have the front end alignment set up by an Alfa specialist who has a decent in-house alignment rig - and knows how to use it. You may have a tad too much toe.

jayarr · January 24, 2018, 09:06:29 PM

Hi all,

thanks for taking the time to provide observations and advice. With the next Broadford a few months in the future, I've got some time to make alterations that are must haves.

As the wear on the outside edge is significantly higher than inside edge and centre even for other tracks, I think a little more camber is in order. As are the poly bushes.

Alternate tyres for track days - this is next level commitment beyond arrive and drive, this means carrying 4 tyres to the track - the mito is still a daily driver.

Question : Are howling (road) tyres a good thing? Or something to be concerned about?

Evan Bottcher · January 24, 2018, 10:30:25 PM

It does depend on whether you wish to compete for points in standard class, or are happy to compete in modified class. Some people are aiming to be competitive in class, others don't care and just want to have fun.

Poly bushes are counted as a modification, so would put you in modified class.

There are options in 'ultra-high performance' tyres that may perform much better than what you've got but are still not an 'R' type tyre - so they don't count as a modification under our rules. They'll be better on the race track, but probably won't last quite as long on the road?

If you decide you want a set of dedicated track wheels and tyres - I'd still question whether you need to carry them to the track. You could fit them at your leisure at home before an event, drive to the event, drive home, change them back later. Race tyres wear more quickly than road tyres, but driving up the freeway to Broadford or Winton isn't going to kill them too quickly. I drove our car to the track and back on R tyres for years and never considered it significant wear, especially compared to what you do to them on the race track!

Road tyres howl when they're pushed beyond their limits in my experience, I don't think it's a good thing or a bad thing, it's just a thing.
For reference, here's Sheldon pushing his 156TS: https://www.youtube.com/watch?v=iOWxw5o3XBg