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Wear on outer edge - wider tires help?


turbogrill
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Hi,

 

After 8 hours we get quite a lot of wear on the outer edge of our tires. Plenty of thread left (re71r)

 

Would going from a 17x9, 245 to 17x10 255 help with the edge wear?

 

Camber is maxed out without taking points and I am running sway bar on stiffest. (Maybe a skilled person could fab something but not feasible at the moment).

 

Car is a nc miata, 2500 lbs with driver.

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Could be. 

 

I always try to go back to basics when figuring things out. Static camber, suspension geometry, sway bars, springs, sidewall stiffness, rim width, etc, all need to considered and optimized to get the tire to the ideal dynamic camber for max grip and tread life. Somewhere between the chassis and the road, something is allowing the outer edge to wear more than the centre of the tread.

 

The usual crutch is to use more static negative camber to compensate, but you're already there. A harder bushing might be enough to reduce flex, or you might want to redrill the inner pivot of the upper control arm for more camber and different geometry, or add more caster to get more camber when turning the wheel, or ... 

 

I don't know the Miata well enough to say, "do this" and solve your problem. You may have to sneak up on it with several small improvements rather than one demon tweak but I'd start off with looking for compliance and how to reduce it.

Edited by mender
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6 hours ago, turbogrill said:

Hi,

 

After 8 hours we get quite a lot of wear on the outer edge of our tires. Plenty of thread left (re71r)

 

Would going from a 17x9, 245 to 17x10 255 help with the edge wear?

 

Camber is maxed out without taking points and I am running sway bar on stiffest. (Maybe a skilled person could fab something but not feasible at the moment).

 

Car is a nc miata, 2500 lbs with driver.

I can't answer the OG question...but what has been done as far as tire temperatures / pressure optimization? I don't have adjustable camber (e30) and have to manage tire temp via pressure adjustments.

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A tire temp probe will tell you whats up.

 

How much camber do you have?

 

To answer your question... maybe?

 

A larger tire will help dissipate heat more (which is really the reason to go a wider tire for endurance racing).

 

However, if you are still only heating the outside band, it's still gonna do bad things.

 

If you are at less than 2 degrees,  you need to get more camber most likely.

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Definately go through all suspension settings and document everything.  Toe, camber, caster, tire pressures and temps.  Easy button is normally camber.  But I would definitely check that all the bushings are good and not worn

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We had the exact same problem on our Civic and solved the problem with a better alignment (have to thank Jay at Powersports Garage again) and increasing the tire pressures by 3lbs.

 

Tire pressure is the quickest and easiest thing to do, check and measure so it can't hurt to start there.

 

 Any advice from Mender is also great advice. He has helped me a thousand times without ever knowing it!

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1 hour ago, Team Infiniti said:

Knocked the toe a little @ Daytona, no one noticed till back home, inside worn out on the RF, took the whole corner apart looking around for something.

I was gonna mention toe.  However, that is usually an inside edge issue as you stated.

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Thank you for all the replies.

 

When we did COTA with WRL we had 'EC' suspension (stiff entry level coilovers) and we didn't experience as much wear as with our 0pts setup (bilsteins and street lowering springs).

I will see if I can stiffen up the front a little to reduce push. Will also experiment with tire pressure and get a pyrometer.

 

My goal is to able to run one set of re71r a whole weekend, I don't want to buy 8 tires @ $200 each weekend. But I am fine buying 4 new tires for each weekend (and finish them of during practice). 

 

The fastest laptime we have done was after 8 hours on re71r, so I think there is plenty of left after 8 hours. But I am not sure they will survive 16hours due to the edge wear.

 

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21 minutes ago, Team Infiniti said:

If that tire was cheaper or known to last a whole race I wouldn't be opposed to them in Champ.

 

Those with large budgets can, and do, exercise their wallet.  Bad for cheap/entry series racing optics.

 

 

Totally agree, 8 tires a weekend is a big difference vs 2 tires a weekend (RS4s).

 

I think if I we can get it down to just one set then it's not that bad, $50/h (RE71r) per person vs $10-25/h per person (RS4s).

 

I am pretty sure that many teams would like to run RE71 if they could but their cars are to heavy (changing during the race is obvisouly nonsense).

 

I think Lucky Dog forces the use of RS4. I don't think that is crazy but I guess then it's more rules and this forum will explode if that question came up. (would probably make internet collapse).

 

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