Boyes50
Boyes50 New Reader
3/31/20 12:55 p.m.

So.

Last season, I ran 205/55R16 Westlake SA57 Tires. My oval track class requires at least a 400TW rating on the tires. Directional is permitted, no winter tires. The outside tires, especially the RF tire, gets absolutely melted and wears after 3-4 races. I have the max allowed camber and the car is very heavy compared to others in the class (2,700lbs).

I have purchased Dunlop Direzza DZ102s this season. These have the same treadwear as the Westlakes, but are obviously more expensive. My question to everyone here who has run lots of tires for Chump Races and such, do tire prices and quality of tires increase how well the tire performs and if how they handle temperature? Or am I just paying for a name brand? I run General AS-03 on the inside two tires and theyre holding up well, but I believe the inside tires simply are not getting loaded nearly as much. I'll attach a photo of the Westlakes after championship night last year. If you can imagine, the tires lost a bit of traction when these outside treads melted completely off. 

Make suggestions. Anything is appreciated! I also purchased 16x7 tires this year and was thinking about running 225/55R16 on the outside now. Do wider tires help spread the melt out? 

L5wolvesf
L5wolvesf Reader
3/31/20 1:13 p.m.

I'm guessing asphalt but please confirm. How much banking? Do you take tire temps at all?

Boyes50
Boyes50 New Reader
3/31/20 1:15 p.m.

In reply to L5wolvesf :

Asphalt, 1/3 Mile, Moderate to High Banking? Not advertised but definitely fairly steep banking. I do take tire temps, with the 3 degrees of camber the tire temps are as close to even across the face of the tire. 3 degrees is the maximum we are permitted to run, definitely 5 degrees would help the car a lot

L5wolvesf
L5wolvesf Reader
3/31/20 2:00 p.m.

With temps within 3 degrees across your camber is as close to perfect as you can realistically get. I presume the temps are takes with as little delay after the run as possible. If so I would look elsewhere. What is your toe setting? How does the car handle?

 

On the banking, is it the same bottom to top, or? Where are you running mostly on the banking?

Boyes50
Boyes50 New Reader
3/31/20 2:03 p.m.

In reply to L5wolvesf :

The car has a severe push. I removed the front sway bar for this season to hope to get the car to rotate more, and stop lifting the inside tire off the ground. The banking is steady from top to bottom. Again, the car is very fast compared to other cars in the class and quite competitive, I just wanna save tires and make the car rotate. 

I run the bottom of the race track. Moving up one lane on the track doesn't affect tire temperatures. Temps are taken with a Mac Infrared Gun within a minute of coming off the track.

iceracer
iceracer MegaDork
3/31/20 2:22 p.m.

Instead of softening the front, stiffen the rear.  Adhere to the old rule.

More caster could help. gives more camber in the turn of the right kind.

Can you use spring rubbers ?

It is important to keep the car from leaning.   The banking helps.

 

 

dps214
dps214 Reader
3/31/20 2:23 p.m.

FWIW tire temps with an infared gun isn't necessarily accurate to the tire internal temp which is what's actually important. But if you're limited on camber then temps don't really matter because you can't really do anything more than you already have.

As for tires, my experience is that in anything over about 300tw, performance ability is pretty much a crap shoot because that kind of heat and loading just aren't considered during the design or testing of the tire. And even within the 300TW range there's tires that look and drive very similar, wear at similar rates on the street, are similarly priced, but some put up with abuse reasonably well and others melt the outer tread blocks off over the course of a single autocross event. I'd say your best options are a) look at what everyone else is running b) buy every 400TW tire in sight and do some durability testing and/or c) buy the cheapest thing you can find and accept that you're going to be replacing it constantly.

Pete Gossett
Pete Gossett MegaDork
3/31/20 2:27 p.m.

My guess is the tires are chunking like that because they're getting overheated. I think flipping them on the rim and/or swapping front to rear on the right side might be the only other way to get more life from them(other than iceracer's suggestion to stiffen the rear). 

Boyes50
Boyes50 New Reader
3/31/20 2:36 p.m.

In reply to iceracer :

Unfortunately, we can only remove and not add. So I could loosen the front, but not add anything to stiffen the rear. Most other Cavaliers and Cobalts have removed the sway bar. I can use 1 spring rubber per corner, and the best results were from adding one to the RR and LF, and nothing in the other two corners. There is no caster adjustment on these cars. I would like to keep the car from leaning. Thinking I might need to add one to the RF to help control the body roll without the sway bar. 

Boyes50
Boyes50 New Reader
3/31/20 2:37 p.m.

In reply to dps214 :

Is there an ideal way to measure the temperature? I am open to suggestions. I am thinking I agree with you. I am gonna try these Dunlops, and if they burn off the same I'll just go back to the Westlakes. They did seem to work well for a $80CDN tire.

Pete Gossett
Pete Gossett MegaDork
3/31/20 2:52 p.m.

In reply to Boyes50 :

Using a tire probe will give more accurate results than an infrared thermometer, but I'm not sure if it's enough of a difference to impact your ideal tire pressures. 
 

It's probably not allowed, but if you can drain the shock oil & replace it with heavier weight motorcycle shock oil that can be a hillbilly way to add some stiffness. 

L5wolvesf
L5wolvesf Reader
3/31/20 5:43 p.m.
Pete Gossett said:

In reply to Boyes50 :

Using a tire probe will give more accurate results than an infrared thermometer, but I'm not sure if it's enough of a difference to impact your ideal tire pressures. 
 

Agreed on the tire probe - you need a reading from just below the surface.

What are your toe settings - front and rear?

CyberEric
CyberEric HalfDork
3/31/20 5:47 p.m.

Curious, what kinda car? 

Looks like maybe a Mazda Protege?

Edit: sorry missed that post.

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