Cal Club Autocross Forums

Sooo I go out to my car tonight after work, and what do I see... 4-5 thumbnail sized pieces and 2-3 smaller pieces missing from the outside edge of my front left tire. They aren't really very deep, and there is still depth to the tread left below them. I'm reluctant to call this "chunking" because it's not the delamination of entire tread blocks from the base layers of the tire.

I don't really know how/when I did this, it could have been on my last two runs on Sunday, but if so I didn't notice it for the whole rest of the day or yesterday, and it really jumped out at me from a great distance today.... It's really weird.

So, what do I do now? I could rotate them to the rear (which isn't wearing as much anyway, I've been really bad about my tire rotations, need to do that anyway) and keep running them. I could have the tires remounted on the rims in the opposite orientation, which would put the these spots on the inside, which doesn't wear as much (clearly I could use more camber, but I've got all I'm going to get out of the Miata stock adjustment bolts)... Could bring both rear tires to the front and put new sticky tires on the rear....

If I show up at tech at one of our events or a PCA event with a tire looking like this, will someone refuse to tech me?



Maybe I need to be running more pressure.... I usually run 35.5 in the rear and 36 in the front.... But if I'm rolling over onto the edge of the tire like this, maybe it's not enough...

Looks like a lack of camber, and to low of pressure to make up for it.

In case anyone is curious, these have ~117 runs and ~4000 miles on them since I had them put on before the 3/1 Championship.

... or you could buy our SSR's with those long lasting RE-11's ... but we have to know before the Porsche Event this weekend ... unless you want us to use them up this weekend.

Having over 200 runs on my Dunlops, I'd agree with Jason and would start with too low an air pressure for the tires. It's hard to tell, but I seem to see a little too much roll-over on the tire. I did flip mine on the rims because of the lack-of-camber-thing - the outside edge just gets burned away but the inside holds up really well. This is life without camber.

Agree with Tom.....and judging from the roll-over I'd say you need to add about 3-4 psi at the least.....and you should be good to go......however, I'd also flip the tires on the wheels now....start wearing the insides instead.

In my S2000 (with max. camber) I run about 38 psi all around so that should be a ballpark number for you (similar to Miatae with tire pressures I found).

Reijo

That's called blistering. The tire tread in those localized areas got too hot. Listen to the suggestions from the folks above.

Some of the above posters have way more knowledge than myself..... so take my comments with a grain of salt.

The pressures you mentioned are (just) above what most Miata owners have told me they run. Most, across a large span of tire types, and driving capabilities, are in the 30-36 lbs range, most with fronts several lbs higher than rears.

Though I don't know your specific tire, maybe it's different. I've settled in on 35 front, 32 rear, across the Falcon Azenis (14"), Bridgestones R11 (15'), and Dunlops StarSpec (15") I've run to date.

Noting the little triangle wear mark imprinted on the tire in the photo, it doesn't look like your rolling the edges beyond what I was told many years ago to run to. I may have been given bunk info????

Were you cooling your tires? It was hot out. That alone may be your cause.

Then again as stated above, some of the other posters know more than I.

Even with the soft sidewalled Bridgestone RE-11's we only run 39/36 with our Miata. With the Z1's ... same size as yours ... I think we were down to 36/33 ... and never had any evidence of Blistering.

Island Tires in Pasadena is THE place in our area to go to have any tire work done ... $10 per tire ... to have them mounted, flipped, etc. Great guys.

Let's take a look at your slo mo video to see if we can see how much tire roll over you're getting. As Craig said, that doesn't appear to be the case. We never cooled our Z1's ... but it wasn't that warm when we ran them if I recall correctly.

"still processing" by youtube

slo mo video: http://www.youtube.com/watch?v=d76aYwPjzY4

http://www.youtube.com/watch?v=QDZrN-3j6ug

John Coffey wrote:That's called blistering. The tire tread in those localized areas got too hot. Listen to the suggestions from the folks above.

I found that the Dunlops do like heat at all and that outside front edge takes all the punishment. Once I started spraying them I could keep them performing - without the water and letting them get too hot, they went away pretty quickly.

I think Tom has a good point. Be sure to water your tires. It has been very hot! They don't like the heat. I think TIm (white S2000) had the same problem with his Z1's.

i saw someone with a yellow s2000 completely loose some of his outer tread block of his Z1's

think about your situation only 10 times worse to where the outer block was coming off

this happened with a guy who was drifting one or two sessions and not autox... not super heavy drifting and the tires were pretty new.. i found it very strange and questioned the build quality of the tire

Darren Cole wrote:I think Tom has a good point. Be sure to water your tires. It has been very hot! They don't like the heat. I think TIm (white S2000) had the same problem with his Z1's.

Yep, they got superhot when I ran them. I would have watered them had I known they'd become this bad. They definitely died from heat cycles as they had plenty of tread left when they started chucking.

Timothy Aing wrote:

Darren Cole wrote:I think Tom has a good point. Be sure to water your tires. It has been very hot! They don't like the heat. I think TIm (white S2000) had the same problem with his Z1's.

Yep, they got superhot when I ran them. I would have watered them had I known they'd become this bad. They definitely died from heat cycles as they had plenty of tread left when they started chucking.

I haven't seen that happen before, and I've gone through many sets of Z1s. Although I do start with shaved tires.

What pressure and size are you running?

Rick

Timothy Aing wrote:Yep, they got superhot when I ran them. I would have watered them had I known they'd become this bad. They definitely died from heat cycles as they had plenty of tread left when they started chucking.

Note to self: get new water sprayer.

Richard Jung wrote: I haven't seen that happen before, and I've gone through many sets of Z1s. Although I do start with shaved tires.

What pressure and size are you running?

Ran 35f/32r. 225/45/17 in front. 255/40/17 in rear.

Driver side front looked the worst. Passenger side front was starting to do the same. Rears were in a bit better shape. Who knows, maybe it's my driving

Timothy Aing wrote:

Richard Jung wrote: I haven't seen that happen before, and I've gone through many sets of Z1s. Although I do start with shaved tires.

What pressure and size are you running?

Ran 35f/32r. 225/45/17 in front. 255/40/17 in rear.

Driver side front looked the worst. Passenger side front was starting to do the same. Rears were in a bit better shape. Who knows, maybe it's my driving

I have a much heavier car with much worse body roll and tendency to heel over the front tires, but I run considerably higher pressures: 45f/42r.

This happened to two of my passenger side tires back during the fun runs of the May event - they chunked pretty bad and I didn't feel confident driving on them after. I was running 34f, 34r at the time. I only replaced two of the tires and ran the car with mismatched tires (new in the front, old in the back - lol) where I ran 38f, 36r for three months before finally giving in and getting a new set. I ran 40f, 38r at the last El Toro event and 38f, 38r at the last San Diego event.

Oddly enough, I found that running the same front to rear - 34psi - got me over 200 runs. I just changed the alignment so that might change as well.

ya that photo is exactly what i saw happen only the tire was much newer