Wheel offset and tire choices.

A couple of simple questions.

First - wheel offset. If one wheel has an offset of 35mm and another is 40mm, which wheel "sticks out" more? In other words, which one widens the track the most?

Second - Falken Azenis Sports have been recommended, but I've been looking and I'm wondering if the Yokohama A032R or Yokohama A032R S-Compound might be better for racing only? Certainly there's the legality question with the SCCA rules, but I'm also worried about lifetime.....How long will they last sitting on the trailer? How many heat cycles will they take, and will autox get them anywhere near operating temp?

I have no real urge to burn money for a set of tires that I'll never get to work, but if they're the hot item and most of you don't use them because they're impractical...... basically I'd like your opinions.

Sorry to ask all these newbie questions folks.

Offset class 101

What class are you thinking about running? If your going to make it a trailer queen and run ES I'd go with a set of Kumho Victoracers or better yet a set of 710's!

For "street" tires, the Azenis Sport is darned near hard to beat. I ran 8,000 street miles and 120 runs on my first set. They quit sticking if the tire temp gets above 160 F.

The A032R moves you in to "race" tire land, and is the tire of choice for CS, CSP, SM2, etc.

The "race" tire of choice for autocross is either the Hoosier A3SO4 or the Kumho Ecsta V710, either of which will have short life (40 runs?) but lots of stick. They're finicky about sunlight, heat and temperature.

The Toyo RA1 is a better compromise "race" tire versus the relatively lower grip of the A032R and the ridiculously short life of the Hoosier/Kumho. But, they won't be as fast. They will, however, provide more runs per $.

Ok, then here's a followup question.....

Isn't there a class in SCCA that requires steel wheels? Spec Miata or something? The reason I ask is because of these:

http://www.discounttiredirect.com/di...76&yr=1993

Which would go with these:

http://www.discounttiredirect.com/di...176&cs=195

All of which would be mounted, balanced, and shipped to my door for $368 plus tax.

Go with the RA-1s and you can run at the track with Race rubber too.

I would say, especially just starting out AutoXing that tightening the nut behind the wheel is gonna make more of a difference than having super competitive tires (plus they're like crack, expensive and addictive).
I've also heard some proffessionals say it is easy to start learning cage driving with a non race tire. B/c they give alot more warning before they let go.

Chris

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Originally Posted by OUTRACE

Ok, then here's a followup question.....

Isn't there a class in SCCA that requires steel wheels? Spec Miata or something? The reason I ask is because of these:

http://www.discounttiredirect.com/di...76&yr=1993

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I think those would be more for snow tires! :shock: :lol:

Spec Miata has a Spec Rim, but it is not a Mazda Rim forget who the supplier is this year! SCCA doesn't have a steel rim class that I've ever read about.

Not trying to be a smart ass but before you pull the trigger on the POS Steel Wheels you may want to do a bit more research! :wink:

Actually Spec Miata doesn't have a spec rim, they just specifiy the size and that it can't be under 13lbs. Rules vary slightly depending on where you run, but thats all I've ever seen.

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Originally Posted by EvilSpeeder

Actually Spec Miata doesn't have a spec rim, they just specifiy the size and that it can't be under 13lbs. Rules vary slightly depending on where you run, but thats all I've ever seen.

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You are correct I was thinking tire (contingency $$$) not rim..... :oops:

"I would say, especially just starting out AutoXing that tightening the nut behind the wheel is gonna make more of a difference than having super competitive tires (plus they're like crack, expensive and addictive). "

I fully agree, but I'm of the mind that it might be a good idea to replace the 185/65/14 Douglas All Weather Radials that the car wears now. Believe me, these rim protectors give plenty of "early warning". :lol: WalMart should be proud to be selling tires that show NO effects of an autox. :shock: (Seriously, you can't tell I did anything this weekend. :roll: )


"POS Steel Wheels you may want to do a bit more research!"

Wasn't really planning on "pulling the trigger" per se, I just seemed to remember that there was some mention of steel wheels somewhere and wondereed if this kind of wheel might serve two masters. (It happens seldom in racing, but sometimes a guy gets lucky.) I'm actually picking up a set of stockers tomorrow anyway.... and asking questions on here sorta qualifies as a type of research.... You folks are a great source of info. Thanks. :D

First answer: Offset is the distance from the hub mounting surface of the wheel to the centerline of the wheel. A positive offset means the wheel seat (mounting surface) is outboard of the centerline, a negative offset means it is inboard of the centerline. Most modern cars tend to have positive offsets (the Miata is no exception). A +35 wheel will move the seat inboard, which will in turn push the wheels further out towards the fender lip.

If you'r eplanning on staying SCCA Stock legal, be careful what offset you choose. Section 13.4 of the SCCA Stock CLassifications Rules states:

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Any type wheel may be used provided it complies with the following: it is the same width and diameter as standard, and as installed (including wheel spacers if applicable) it does not have an offset more than +/- 0.25 inch from a standard wheel for the car. The resultant change in track dimensions is allowed.

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Your year Miata came with +45mm wheels as OEM equipment, That means you have to choose a wheel with an offset somewhere between +38.65mm and +51.35mm (1/4" = 6.35mm). A +35mm wheel would not be legal on an NA Miata in Stock.

As for steelies, my first set of track wheels were steelies off of a Honda Odyssey (right size & offset for the Prelude I had at the time). They're a great wheel to start out on, because when you make the upgrade to lighter aluminum wheels you won't be out as much moeny as you otherwise might have been. Used NA Miata "daisy" wheels are also a good choice, as I see sets going on ebay for around $150 all the time (wish I could buy a set of Stock legal wheels for $150 :? ). They'll also be lighter than steelies, and as an ex bike racer I'm sure you already know that weight is the enemy.

If you're going to buy R compounds, I'd skip the A032Rs. I've used them, and I think they're only marginally better than an Azenis as an autocross tire at three times the price. They're better on the track (more heat resistant), but they're still a slower track tire than any of Kumhos compounds or Toyo RA-1s.

Like Chris mentioned, I would really urge you to spend at least half a season racing "cages" on street tires before making the jump to R compounds. There is no question that R tires are faster, but they tend to mask some bad driving habits. It's best to learn to be smooth and control the car on street tires first (imho), and then make the move to R compounds. Not only will you be a better driver for it, but your R compounds will likely last longer to, as you won't be overdriving the car as much. I'd recommend starting out on Falken Azenis. They're cheap, sticky, consistent, not nearly as fragile or environmentally sensitive as R compounds, and cheap. :wink:

However, if you want a good, dual-use R compound that will work well on the track and for autocrossing, give the Kumho Victoracers a try. They last longer than the "top dog" autocross tires (120+ runs out of a set of unshaved Victoracers compared to <40 for Hoosiers S04s and ???-probably 50 or so for Kumho V710s), they're relatively inexpensive (at least as far as R compounds go), and they're heat resistant enough to work well on the track.

RA-1s are a good, consistent, long lasting track tire, but they don't heat up quickly enough to be an effective autocross tire on a lighter car like a Miata (a 3400lb Camaro is a different story). Plus, in my personal experience they're not quite as fast as the Victoracers at the track, although they don't tend to go "off" near the end of a run session like VRs do.

While Steel wheels may be a good choice for a Prelude with an automatic! :P

Mazda has offered a bunch of nice wheels, the wagon wheel comes in around 12 lbs. a piece where the Mazda OEM steel wheel tips the scales at 18 lbs. a piece! That's a 24-pound difference when you bolt them on the car! :shock:

Miata Wheel Info