Are Discount Tire Certs worth it for AutoX Tires?

[CaptainSlow]

About to try and buy a set of Pirelli P Zero Nero's for AutoX. Since I'm planning to take them to the track and then swap them, is it worthwhile to get the certificates?

I'm pretty sure there's a low chance of cert-worthy damage occurring if it's only being used for autocross. Anyone have experience otherwise? Still new to autocrossing, but hopefully going to make it more of a regular thing.

 

[RAAMaudio]

I would take more time picking tires, never seen any review, testing, etc, saying that tire would be best for autocross.

Let us know the mods and class you intend to run as likely better tires to choose from and some of us will gladly help you pick the best ones.

If not properly inflated, not spraying between runs if needed, will wear out with less miles etc...you could damage them and so have to ask yourself if you would feel right getting warranty coverage that is not what they were intended to be used for. I have ripped chunks of tread off brand new tires, decades ago, when learning what is needed to do things right for autocross, best to buy tires intended for the use or have whatever you pick shaved before using them.

 

[CaptainSlow]

Interesting... I never thought that tire chunks flying off would be a thing in autocross. I'm glad I checked here first because I didn't realize that. A quick google search also proved your point here...

I was hoping to keep running in the HS (H Stock) class so there's the 200 minimum treadwear. The only mods I have are the RMM and the OCC, which I'm assuming don't push me out of stock. Definitely also not crazy enough to run slicks yet. Plus they're expensive. I wanted to improve my driving skill first before trying to upgrade the car's power/performance too much (One thing I could've done last time was turn on "sport mode" as I completely forgot in the moment, though my times dropped ~5 seconds over 4 runs)

I'm still new to the sport, so I can't quite comprehend/haven't experienced the importance of the tire pressures yet, though I sort of get the concept. I did see the post about the Michelin sidewall getting ripped up and I think the consensus was TP was too low, right?

Also, how much of an impact does spraying between runs affect tire wear? I saw a number of folks using the weed killer pumps to spray water. To me, since I'm focusing on driving skill, it seems a bit overkill at this point but it sounds like it can prevent excessive wear?

On the topic of shaving, does it help significantly? Is it something I should be looking into for the treadwear range I'm considering?

AFAIK, for the stock 17" wheels that would qualify for HS, people here have run:

• BFG G-Force Sport Comp 2**
• Bridgestone Potenza RE760 Sport** (sounds like it would be better than the BFG's from this thread)
• Bridgestone Potenza RE050A (stock, seemed fine to me? I don't know good from bad..)
• Bridgestone RE-71R (seems to be rec'd by [MENTION=1229]Phreak[/MENTION] here
• Michelin, Pilot Sport A/S 3 (not rec'd by [MENTION=3766]velryb[/MENTION] here

** means I can get it at the local Discount Tire in Houston.

I know 16's are still HS allowed, but I won't be shifting to them anytime soon since I already acquired a set of stock 17's wheels for a good price. I realize stock wheels are heavy and what not, but I'm mostly just trying to have fun and get better at driving fast and not so much being the fastest there. As a side note, I'll probably upgrade the daily set to Michelin's once the RE050A's runs out.

 

[CaptainSlow]

I think I may have found my own answer...

Direzza ZII Star Spec seems to be highly recommended for what I'm going for. I had limited my selection to the stock 205/40/17 instead of trying other sizes like 205/45/17.Guess I'll see if I can get a set of them for a good price...

 

[Phreak]

If you are doing it for fun, then the Direzza ZII Star Specs are a great pick. If you are out to get the absolute best competitive edge, then the RE-71R's. Basically everybody at the national events who is there to trophy is running the RE-71R's this year.

The thing is that the Direzza ZII Star Specs are still extremely competitive and they last twice as long. That makes them a great tire for local events or really anybody who is just out to have fun on a budget.



For sprayers, I just use a weed mister. If the tires start getting too hot, they practically start melting away. Some people like to bring temp guns out, they are fairly inexpensive and you can keep an eye on it easy with them.

Personally I like the chalking method + bleeding air off after each run. I put chalk on the outside and then after a run I can see how much of it rubbed away (the idea is to see how much the tires are rolling over). If they are not rolling over to the edge of the tread I drop a bit of pressure out, if they are rolling over past the edge then I add pressure. Usually after each run the heat will raise pressures by 3-5psi, so you have to bleed it off to keep them perfectly tuned.

When you get your tire pressure just right... boy it makes a world of difference for traction!

 

[CaptainSlow]

So much to keep track of now...Great information so far!

Since I'm not trying to be the best, and I like the idea that they last a bit longer, are the Direzza ZII Star Specs in 215/40R17 or 205/45R17 "better"?

From what I know, it sounds like the 215/40R17 would generally be better performance wise because the wider tire and shorter side wall (86mm vs 92.25mm), but would the handling be affected significantly due to the mismatched tire width and wheel width? The 215/40R17 is also a best seller on Tirerack which I guess points to it being the preferred size.

 

[RAAMaudio]

Great info posted, listen to it, follow it, will help a great deal and you are far better working on your driving instead of modding the car for now, glad you understand that

There may be a valuable trade off going with either tire. Taller sidewalls can flex more but the 1/2' narrower section width may make up for that. Heavy wheels slowing you down already, 8 less lbs of rotational un sprung weight is a lot more than many comprehend the value of. But, the wider tread width may still be faster though it could be harder to drive at the limit which is what autocross is all about.

If you go to the right forum you can see what experts on the tires have to say, those of use with a lot of experience can help a great deal but if we have not ran a stock class car, ever, with the current tires available on various rim widths like me out of many cars I have setup and ran, our advice simply cannot be the best.

I believe you will learn more and likely be faster sooner with the easiest to drive tires so you can focus on technique which is hugely important in autocross, let a really great FWD or most any really fast driver give you a ride in your car and it will really open up your eyes.

Unless it is really hot out or you are over driving, have two drivers, etc...you might not need to spray your tires.

Best way to take temps for autocross is at the outer edge, middle, inner edge, right after the run, even temps is best, a bit warmer on the inside is usually better than the outside using an infrared meter as the heat is not as deep in the tires like on a road race session. I have done this so much I just use my palm most of the time, faster and it is pretty calibrated after all these years

Another thing that helps, dial in all the negative camber you legally can.

A slight bit of toe out usually helps turn in as well but not so fun on the street as the car might wander and be prone to follow grooves in the road.