16in wheels, ZG flares, perfect tire combo 77 280Z

[Wheeliegeezer]

Okay, before everyone piles on and tells me to search the forum, I have spent months reading here, studying websites like Fitment Industries and gallery pics and YouTube on my wheel and tire choices. Here’s the deal. 77 280 coupe. Cut wheel wells, standard ZG flares 1 7/8ths front 2 7/8ths rear. Silvermine coilovers. Wilwood front 4 piston disc brakes drum rears, lowered one inch.  Now, 17 inch rims look wagon wheel ish, 15 too small so 16 inch seems just right for brake clearance  and rubber should be available. Going with that, I want a flush fit as close to the flare as possible, no or little stretch, no rubbing, and no spacers. I want the offset correct to get as wide a tire as I can. Not opposed to stagger, so with the slightly wider rear flare seems like maybe that is the way to go. Otherwise, I would have to go a little more negative offset on matched rims to get the outer edge flush on the rear to the bigger flare. Would like a deep dish machined wheel. Can someone point me to a thread or their setup that is the silver bullet here. Closest I have come seems to be a guy running 9.5 inch rims and something like a 245-40-16 but he didn’t specify the offset.  Help me end this madness please.

[AydinZ71]

Sorry, can't help you. Have you tried Facebook? 

[Wheeliegeezer]

Best info so far is Barry at Bigwheels.net……found him on an old post. Very, very knowledgeable and helpful. Toughest call is deciding to go to 17s or not. I’m considering it due to way more tire wheel combo choices. Still looks a bit tall but if you get a deep barrel style is helps the look . Now have to do measurements precisely when the suspension is bolted under the car prior to paint. 

 

[AydinZ71]

There might be a few folks on here that may know, but in general most of us active folks are gearheads focused more on performance (street or track). You are looking for something very specific from an aesthetic perspective. I will say, the look you are going for seems to be very popular and several people are trying to replicate that look. 

 

From a technical perspective, just keep-in-mind the closer your tires are to your flares (horizontal plane), the less suspension travel you will have before they rub. Unless you form custom flares with a similar profile to your wheel/tire, your suspension will suffer from trying to optimize the "look". You will get the "tucked" look while having room inside the wheel well for travel. That would be a lot of work and it may or may not look any good. Just some food for thought. 

 

I would try to strike a balance between getting the tucked look without going over-board. Those "slammed" cars you see in JDM magazines etc... well, they are cruisers. Similar to the old school lowrider culture. Not ideal for a daily, comfort, or maneuverability. 

[74_5.0L_Z]

I have a 260Z with SubtleZ body kit and Ground Control coil-overs at all four corners.  The SubtleZ kit provides an additional 1.5" of clearance between the fenders and tires compared to the stock fenders. 

 

The car currently has 15x10 wheels with a 5.25 inch backspace.  On these wheels, I have run Hoosier 275/35-15 and Avon 23.0 x 10.5-15 race tires.  I run no spacers on the rear and use 1/4" thick spacers on the front. 

 

I have previously ran 16x8 inch wheels with a 5 inch backspace on all four corners with no spacers and the stock body work.  Clearance was perfect with 245/45/16 Hoosiers.

 

The key is getting the backspace correct to clear the coil-overs.  Then specify you width to fill the fender.

 

For 15" wheels, the maximum backspace that you can run is 5".  Any more than 5" backspace requires a spacer on the front wheels.  The rear wheels can accept a little more backspace than the front generally.  On my car the rear tire clears the strut by ~1/4" with 15" using a 5.25" backspace. 

 

The larger diameter wheels can run a little more back space, but then you get into making custom wheels.

The pictures show the car with the Avons and the Hoosiers.

Edited July 21, 2022 by 74_5.0L_Z

[Wheeliegeezer]

Yes agreed Aydin71, I’m not trying to build some un driveable show car, I want to autocross a little and enjoy spirited street driving. No intention of putting rubber out there for no reason. Fact is, I will prolly only be pushing 225  or 250 hp so not needing super fat rear in the equation. There’s always a good compromise.

74_5.0L_Z…….thanks for sharing all those stats…….helpful to know what the backspacing needs are. Barry will help me get the width figured out once I know backspacing with either 16 or 17 inch wheels and then the right offset will allow me to run with no spacers, thats the goal. Love your SubtleZ body…….carries the looks well. Some of the wide body kits are so radical you kind of lose the plot on the Z altogether. 

[Sanchez]

I’ve been looking into rim/tire combos recently and have settled on 17’s partially out of necessity, and partially out of trying to use as many easy to find parts for replacement in the future should I need so. I’m going to be using the Apex Engineered 8.8 subframe and front uprights which use 350/370Z brake parts very few 16” rims will clear and I need a 5x4.5 lug pattern. It’s looking like a set of Rota RK-R will be my choice 17x8.5 with -10 offset under marugen shokai flares and the new Apex coil overs. Should fit nice with lots of travel and flush looks. With VQ power I’d like to run 225/45r17 or 245/40r17 on all corners, again because staggered makes rotating tires a problem. A lot of the guys on here will tell you don’t go staggered for handling which I agree with especially if your suspension is staying mostly stock and you spend more time cruising than racing. Where I differ from some of people is that I think 17’s are a good look on the Z and modernizing the suspension even with heim joints instead of rubber bushings you can run a 225/45 or 245/40 tire without the ride being anymore harsh or fairly decent road/highways than a stock Z on taller tires.

Compound and tread are more important for traction than width, and given you want 250hp I’m assuming a mild turbo L28 is your goal. You won’t have instant peak torque like a diesel or modern car with VVT-i, VVEL, etc. that will give 200lb-ft right off idle. Choose the rims you like for looks, the tire width you want for suspension travel and firmest, and then the tire compound and tread for performance. Depending on your hearing I’d bet you’ll be happy with 225/45r17 tires, and might actually like the look and the ability to not have to wait a few days for tires like you might have to for anything performance oriented that is 16” or less. My beater Altima got new basic fuel savers/daily 16” and I had to try 4 places in a major city before I found a place with the correct profile. 

[Michael]

On 7/21/2022 at 9:27 AM, Wheeliegeezer said:

Yes agreed Aydin71, I’m not trying to build some un driveable show car, I want to autocross a little and enjoy spirited street driving. No intention of putting rubber out there for no reason. Fact is, I will prolly only be pushing 225  or 250 hp so not needing super fat rear in the equation. ...

 For 225-250 hp, why not just get 15x7 wheels with 225-50/15 tires, in your choice of tread compound (from passenger radial all of the way to full track-only), and call it a proverbial day?  In fact at that power level, I'd be befuddled as to the need for flares of any kind.

[AydinZ71]

Because they want to make it looked “slammed”. Or whatever the kids call it these days. 
 

im kidding, I think it’s cool that everyone’s got a style in mind. I agree it’s not a performance oriented decision though.

 

Z’s set up for racing rarely go wider than 15X7 because of a combination of racing rules, reduced weight (both in the wheel/tire combo and the much lighter ~1900lb or less, car), and generally topping out at 250-350 for NA L-series motors. 

 

I feel the early s30’s are closer to a Miata than other popular and larger modern GT cars, in terms of size, weight, and handling. 

[tube80z]

On 8/1/2022 at 12:26 AM, AydinZ71 said:

Z’s set up for racing rarely go wider than 15X7 because of a combination of racing rules, reduced weight (both in the wheel/tire combo and the much lighter ~1900lb or less, car), and generally topping out at 250-350 for NA L-series motors. 

 

I feel the early s30’s are closer to a Miata than other popular and larger modern GT cars, in terms of size, weight, and handling. 

 

I'll let my friends that race in GT-2 know they are doing it wrong  

 

For a street car, you don't need flares for most of the tire/wheel combos being discussed.  One thing that's important to think about is how long will tires be available for your combo.  I used to think 17s were needed to have an assortment of tire choices and now those are getting used less often.  As much as I hate the look of 18s on a classic Z I'm thinking that may be my best option for my street car.  I can tell you from personal experience it's not a lot of fun to have that perfect set of wheels you found for your ride become rather expensive conversation pieces because you can't find the tire sizes you need.  

[JMortensen]

225/45/17s are the same diameter as 225/40/18. I switched from 18s to 17s for ride quality and wheel/tire weight on my GTI. Lost 15 lbs PER WHEEL going from 18s and Pilot Sport all season 550 TWs to Konigs and Conti Extreme Contact Force. Obviously you can get higher quality wheels and all of that, but if you're not going super wide on the wheels there's quite a few tires available in 17s.

[AydinZ71]

19 hours ago, tube80z said:

 

I'll let my friends that race in GT-2 know they are doing it wrong  

 

For a street car, you don't need flares for most of the tire/wheel combos being discussed.  One thing that's important to think about is how long will tires be available for your combo.  I used to think 17s were needed to have an assortment of tire choices and now those are getting used less often.  As much as I hate the look of 18s on a classic Z I'm thinking that may be my best option for my street car.  I can tell you from personal experience it's not a lot of fun to have that perfect set of wheels you found for your ride become rather expensive conversation pieces because you can't find the tire sizes you need.  

 

Ah, yeah I certainly am unfamiliar with GT-2. My perspective is clearly limited. From the conversations I had with Greg and a few others, 245’s Cantilevered slicks on a 15X7” wheel kept the weight of the whole assembly very low while providing quite a bit of contact patch. Of course these are L24-28 NA EP, CP vintage, and VARA cars so greater torque would change the calculus. Fair enough to say you have more and broader experience.  

[Dat73z]

@AydinZ71slightly off topic but what is the rationale to run 245s on a 15x7 instead of a 15x8? 

[AydinZ71]

30 minutes ago, Dat73z said:

@AydinZ71slightly off topic but what is the rationale to run 245s on a 15x7 instead of a 15x8? 

 

Certainly not an expert by by a large margin, but I don't think 245's will work on 15X7 w/ street tires. Hoosier makes these slicks for racing, but even more so they list "Prod, GT" in the description of 245/580R15. Meaning, the tire was specifically designed for production racing where clearly the width of the wheel is limited by class rules. The contact patch is much larger than the wheel width itself, hence "cantilevered slicks". 

 

Using only deductive reasoning, I don't think DOT tires can have a larger contact patch than the wheel width? Recalling Cary and Jon's previous posts, I think they know a lot more about this subject than I do. @tube80z, @JMortensen

 

E-production is limited to 15X7" wheels but that's not a terrible thing given the ~260hp EP L24 and the 245 tires. With Volk TE37 wheels and the hoosiers, the combo is remarkably light! I just weighed the wheel/tire combo with my 13.6lb Koenig wheels and its only 33lbs! Again, no expert but that seems pretty darn light for a 245 contact patch. on a 15" wheel. 

[Dat73z]

@AydinZ71 interesting, so the 15x7 wheel sizing is dictated/limited by class rules?

 

Was just curious because I've seen miata race cars run 15x8-15x10s anywhere from 245-275s. I should probably ask my neighbor who races miatas next time lol

[AydinZ71]

So I am only familiar with the class rules in SCCA EP and ITS. In E-production is sort-of the closest thing to C-production which is no longer a class raced at nationals. Not sure if its still around regionally. ITS is less-modified than EP. higher weight limit, etc. 

 

EP, we are limited to 15X7". ITS seems to limit the wheel and tire widths: 7" w/275. 8" w/225. 

 

It all comes down to the specific spec. line in the particular racing league and class.

 

The point I was making much earlier in the thread is given the power, braking, chassis/suspension limitations of a particular class, ultra wide wheels/tires is not always "better". At some point, you pass an inflection point where the rotating inertia and weight of the wheel & tire starts fighting you and the additional traction from larger contact patch is giving you diminishing returns. If your braking and torque can't utilize the extra grip, that still leaves cornering grip but you are still adding inertia and weight. Now if you had a Z with unlimited brake modifications, unlimited wheel/tire and torque far above what you can get from an NA L-series motors, you can certainly gain a lot from going wider than 7"!

 

As a point of humility, I don't have the first-hand experience of racing for years like others here. This opinion is from many conversations with those that do, but my perspective is narrow. Assume whatever Jon, John, or Cary say supersedes my opinion haha. 

[JMortensen]

Cantilever slicks are weird, the sidewall folds over on itself and so the tires are much wider than the wheels. They look the opposite of stretched tires (see below). I haven't run them myself, but I'm pretty sure you can only get them in bias ply and they need very little camber.

I did run 10" radial slicks on an 8" wheel, they were floppy in slaloms but still faster than street tires. zredbaron has 245s on 16x8s A7s and they are definitely pinched onto the wheels but they work pretty well, not nearly as floppy as my slicks were. Hoosier will tell you that the tread should be .5 or 1" narrower than the rim width, FWIW. If you are buying wheels, you should follow that guideline. If you already have wheels, sometimes you have to run what you have. Worse things have happened.

By way of comparison, my Konig Rennsport 17x8s are 17 lbs and mounted with a racy 200TW tire it is 39 lbs. Slicks are built lighter but ~40 lbs for reasonably priced wheels and tires in a 225/45/17 is not bad, IMO. 

[jhm]

While this has turned into an interesting discussion (largely focused on race-tire/wheel options), I’m thinking it has probably strayed from the OP’s intent.  

 

@Wheeliegeezer, have you considered trying a wheel mock-up tool to determine your optimum diameter/width/offset?

[Wheeliegeezer]

JHM…..on the offset tool, yes…..I have looked at them online. Prolly the best most accurate way to sort this out. The ultimate answer is first to get the completed car up on jacks and measure back spacing, front spacing with the flares installed and see what total width and clearance I have to work with then calculate offset to tie it all in. Barry on this forum from Bigwheels.net has been the most valuable resource I have talked to. Off the top of his head, he said if I was willing to go to 17 inch wheels, he was sure I could run this

 

front 8 in wheel 225-45-17

rear 9 in wheel 255-40-17

If I want to stay with a square setup I might settle for 235-45. 

But he said save the final call till after I measure. 

I hadn’t intended to go bigger than 16 to avoid wagon wheel syndrome but the more I look at pics on Fitment Industries gallery I’m thinking I am okay wiit 17s and there are so many more tires combos with those over 16s. These arent crazy widths really, and I am not racing in a sanctioned series anyway. I have made the decision to go mild turbo on the motor so a wider stance and some traction will be useful without going overboard. Once I get pics of my spacing numbers I will post here and follow up with the combo I end up with. Thanks for all the thoughtful posts everyone. 

[jhm]

If you’re planning to do some auto-x and track days, a square setup will be more economical in the long run...allowing maximum ability to rotate tires front-rear-left-right.  This is particularly important if you choose a softer compound tire.  Wheel spacers and spacer-adapters can give you flexibility to adjust track width, as necessary.  

 

The other option that many folks use is one set of wheels for street use and one, or more, set(s) for track use.  (My wife tells me that I’m limited to no more than four sets of wheels & tires.)