205 or 215 for 17in wheels - Daily Driver and Autox

[mercdank]

It seems that some of the better performing tires that will fit our vehicles tend to be the bigger 215/40R17 size instead of the stock with 205 width. I have been able to find some offerings in the stock tire size, but they are either too aggressive IE for track or autocross use only, or they are not aggressive enough to offer a performance increase over the stock Potenza RE050As.

I do autocross events pretty regularly, my last one was the 9/27, and I have one on 10/18, and then again on 10/25, and another 11/14. I also drive about 70 miles a day in my daily commute, not including extra driving I do for my business which can mean I put easily over 100 miles a day on the car in highway and city traffic.

I am looking for a tire that will give me decent street life, something like 15,000 miles before I have to replace them, and also be significantly better than the stock Potenzas for autocross. I plan on staying with a 17x7 wheel, so 205 and 215 width are what I am looking for. I have been able to narrow it down to these few below. I would really like some feedback or even suggestions for other tires that you think would be appropriate for daily and autox.

205/40R17

• Michelin Pilot Sport AS/3 (after seeing the thread on here about their total failure at the slalom, they are no longer in consideration)
• Falken Azenis RT-615K - these seem like a good balance
• Toyo Proxes R888 - example of too aggressive for daily use, but good tires nonetheless
• Nitto NT01 - again, too aggressive for daily, but a very good tire

215/40/R17

• Dunlop Direzza ZII Star Spec - very nice balance of track and daily, this is a highly considered option
• Yokohama Advan Neova AD08R - another very nicely balanced tire, this is also in the running

Please comment and if you have any other suggestions I would really like to hear them. Thank you for reading.

 

[15performanceblue]

I would do the 215/40/17. If I end up not buying new rims next year, I am going 215/40 on mine. I want the extra width. Being stage 3 with an E30 tune 1st and 2nd gear are useless. Literally cant get traction, So a wider tire and better performance would be ideal. Just my opinion.

 

[mercdank]

You think that the 215 on a 7in wheel is going to be OK on the track? I will be honest and say that I just don't know exactly yet how the width can affect performance, other than providing more grip. I am just worried that too wide a tire might have issues with the sidewalls being compromised at high speed turns, slaloms, etc, or premature tire failure.

 

[Joker328]

You think that the 215 on a 7in wheel is going to be OK on the track? I will be honest and say that I just don't know exactly yet how the width can affect performance, other than providing more grip. I am just worried that too wide a tire might have issues with the sidewalls being compromised at high speed turns, slaloms, etc, or premature tire failure.

I'm not an autoxer, but I would think going wider than 205 on a 7in rim would be less than ideal due to the point you just made about sidewalls (though it seems many people do it), but it may be worth it if you can't get the tire you want in a 205. The tread width for those 215's you listed is about 8", so a full inch wider than the rim width. For autox/slaloms, I would think you'd want a tread that is similar in width to the rim width in order to keep them from rolling too much in the turns.

You may already know all this, but sometimes a slightly narrower tire that is more stretched will actually provide a more consistent contact patch, traction, and responsiveness than a wider tire on the same rim (though things like tread pattern and compound probably matter more). Basically the side of the tread toward the inside of the turn rolls up and you lose the benefits of it, while the sidewall on the outside rolls down if the pressure is too low (like that guys with the Pilot Sports). Some tires have stiffer sidewalls than others, so you gotta do your homework of course. If you go with the 215s and find you are getting too much roll, you can compensate by increasing the pressure, but that will have an impact on traction as well of course.

All things considered, the width will probably not make as much of a difference as the quality of the tire, so get whatever size you need to get to get the tire that you want.

 

[FORZDA 2]

I've autocrossed on the 215/40 Dunlops and won every event entered. They are perfect for stock class wet or dry, but no freezing weather or snow/ice.
You can run the OEM pressures 39/36 f/r COLD pressure and do NOT lower the pressure when hot, let it rise with the temps/loads. I can't emphasize it enough, set the pressure cold in the morning before the sun hits them and don't let any out. If you think the front pushed too much then you're overdriving the tires and need to adjust your driving/technique to let the car/tires give you the maximum grip available.

 

[mercdank]

Thanks for the input guys. I live I Miami, so no ice or snow, ever. But lots of rain.

 

[RAAMaudio]

I am more inclined to run 205 on 8's 215 on 8.5 and 225 on 9's for the maximum performance but that is for road course use.

For auto cross you can change that up quite a bit but you want to use tires designed with that in mind, it is why the 215 Dunlops are working well for FORZDA2 and likely the best tire for your needs, quite a bit lower cost than the Yoko and probably faster as well.

 

[mercdank]

Can you please give more insight regarding the different setups you'd use road racing vs autocross? I wish I knew what you meant in your comparison, but I'd only be assuming I know what your getting at. I'm not so versed in tire selection mechanics, but I'm trying learn. Thanks!

 

[RAAMaudio]

Autocross rules often limit wheel and tire width for the class that ends up with us having to use wider tires than wheels to get the most grip. Since autocross, etc, is at much lower speeds it seems one can get away with a bit narrower wheels and tire manf sometimes design tires to specifically address that, stiffer sidewalls or other methods to help make them work well.

On a road race course where you are going far faster for much longer periods of time you need the maximum feedback possible and a wide wheel with a slightly narrower tire provides that.

Of the tires you listed.
R888
NTO1
They are not street tires, they are race tires with DOT rating only to meet rules that requite DOT tires, you do not want them for the street though I have driven to events on R888 tires I would never daily drive them, they will not last and likely puncture more easily.
They also will not likely get warm enough to provide full grip for an autocross unless you have two drivers running the same group and even then might not.

The Mich is a great tire when used properly which is not autocross, more Autobahn in design and they were not inflated properly.

The RT615k is an old tread design with a newer compound and I have not seen any great reviews of its autocross performance, might be better as a streetable track tire but not quite a DOT race tire.

The Advan is a really good tire but likely more Autobahn than autocross, nobody winning I know of is using them and they are a bit overpriced these days.

The Star Spec is designed and proven to be a very capable autocross tire and good street tire, not great in the rain so you might not want to run them in the rainy season but overall are likely the fastest/best wearing tire for the money when you look at all aspects.

 

[AMontgomery]

Isn't one of the Auto-X governing bodies setting a minimum treadwear standard of 200AA/A? That would rule out the Advan, R888, and NT01. Assuming you want to stay competitive and not just do it for fun that would leave the Direzzas.

Now, me personally, I'm running Advan Neovas in 215/40 on the stock rims. I've reviewed them on this board. My opinion condensed is that they are better than the stock Potenzas in every possible way. Dry grip, wet grip, cornering grip, sidewall stiffness, etc. Ideally, I would want them on 8" wheels to maximize feedback, but only if I planned on being competitive in autocross. Otherwise, I am competently satisfied with them and can recommend them even at there current price, which may be why they aren't used extensively in autocross, though I have nothing to back up that statement.

 

[mercdank]

Thank you!

 

[mercdank]

I'm not sure if they follow the rules exactly, it's more for fun but I'll check. Also, the stock Potenza tire are 140 treadwear so I guess technically can't use them in official events.

 

[AMontgomery]

I forgot where I read that little tidbit, probably when I was doing my research before picking my tires, but if true, it certainly limits your choices.

And the stock tires suck for communicating compared to other options available. They have an extremely weak sidewall, feel them and something like a Neova or Direzza. So a really competitive individual would need upgraded tires anyway.

 

[AMontgomery]

I forgot where I read that little tidbit, probably when I was doing my research before picking my tires, but if true, it certainly limits your choices.

And the stock tires suck for communicating compared to other options available. They have an extremely weak sidewall, feel them and something like a Neova or Direzza. So a really competitive individual would need upgraded tires anyway.

 

[GAbOS]

Read this for the class you are looking to run. Stock starts on page 73

SCCA Solo Rules

 

[AMontgomery]

Quote from provided link. Page 75-76

A. Specifications
13. StReet
1. Minimum UTQG Treadwear Grade of 200.
2. Minimum molded tread depth of 7/32” as specified by the manufac- turer.
3. Listed in a current year or prior 2 years of the “Tire Guide®” and/or the “Tread Design Guide®” (www.tireguides.com).

Kinda rules out everything except the Direzzas.

 

[RAAMaudio]

If you are running SCCA events expect the rules to be followed, especially in a car that is probably in the wrong class as proving to be dominant.

If you are just running for fun you can just run whatever class your mods put you into, only when wanting to be a top contender or winner do you need to stick to the rules for the class you can be most competitive in.

In the 70's I ran a 510 Datsun and used every trick in the rule book I could to beat all the cars with a ton more money into them as they just bought parts and stuck them on if allowed but never really understood that was not the fastest way to go, all things must be setup to optimize every aspect of handling, braking, acceleration, etc....

After that I found it far more fun to just build whatever car I wanted to build to the level I wanted and then run the class it fell into then tweak it here and there to make it as good as it could be. Taking 2nd and 3rd place in what most would consider the totally wrong car for the class was and is far more rewarding to me, especially when I could beat nearly all the "superior" cars and spend a ton less money doing so

I have been invited to be a part of championship winning autocross and road race teams but always declined, I am too independent for that, especially after 20 years in the Navy, have not even had a job since then, had to be self employed.

That said, figure out just want you want to do with the car, make it as personal as you wish and run whatever class you must, make it as fast as possible to be the class winner.

The most important thing and one I have always advised, autocrossing is the best way to sharpen your skills where it means it the most, on your daily drive where things happen in close qtrs with little reaction time. I cannot even count all the times I have avoided a serious wreck by automatically doing exactly what was needed, no time to think, and not over reacting as a huge number of wrecks are caused by.

 

[RAAMaudio]

I was editing my last post when the one before with the specific rules was posted, thanks for digging it up

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I agree, the Dizerra is the only game in town and it is a dang good tire so you are lucky you can get what fits, does not always happen.

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I went and looked at wheel requirements, to bad you cannot go to a 7.5 or 8" wide wheel and lose some weight in the process.

I would search and see what top drivers are using as the 205/45/17 could be faster, certainly should provide more feedback.

It weighs 2 LBS LESS which helps in all aspects of performance.

A bit taller which might keep you in second gear without banging off the ref limiter causing you to lift or shift up and down more often.

The 205 is a wide 205 at 7.6" giving up .4 " in width putting an overly wide tire on a narrower rim is not often the best way to do things but sometimes it is, again I recommend looking into what top competitors run, ask on the SCCA forum, etc

You might want to consider going down to a 16" diameter wheel, there are some lower weight ones which will help performance a great deal, moderate cost, tires are less money...

 

[mercdank]

Thanks for the comments guys, it has certainly given me more to think about and research.

Speaking of 205/45/17, I never occurred to me to look at a taller sidewall. There are more options in that size (Potenza RE-71R for example is 200 treadwear) but the point about the revs is something to consider, as nearly all autocross I have done has been in second gear.

At this point I am doing it only for fun, and to become better at driving my car. I'm also interested in some HPDE courses, but I want to have some more autocross under my belt before then as it is quite a bit more expensive.

 

[RAAMaudio]

I did not read your mod list until now when I was thinking about having the redline raised to make sure you do not run out of gear, not much power to be had on a stock turbo up higher in the rev band but still better than bouncing off the rev limiter. Autocrosses are supposed to be setup for a top speed of 60 MPH but a car like ours can easily pass that speed depending on the course layout.

Looks like you are already out of the stock category

C: (for some reason not cutting and pasting properly) though a little confusing at first glance specifically states any part of the exhaust past the cat can be changed.

Also any mod not specifically allowed in stock puts you out of the class, your IC, piping, Engine mount, tune, likely all illegal.

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I looked up ST class for you.

Allowed items include:

255 wide tires, 9.0 wide wheels, any diameter
Camber kit, front and rear
Intake

Not allowed:

Boost level or controls
IC change
Cat change allowed but seems you must run a cat, not clear but it can be checked by emailing the director of the solo rules, etc.

So, now you have to look at the next class up due to the tune, IC...

Stay tuned