It seems like there is an awkward spot on tires sizes on the FD. I see a lot of people running 9-10.5" wheels, with a staggered width between front to rear. For example: 9 front 9.5 rear, 9.5 front 10 rear, 9 front 10 rear, etc...

Tire-width-to-wheel-width affects how the tires grip -- my understanding is that generally a narrower tire on a given wheel width produces more rigidity in the sidewall, and therefore better steering response. A slightly wider tire on the same wheel produces better straight-line traction.

However, it seems that most people with a stagger run the same width tire front & rear. Isn't this the worst of both worlds? You get the "straight line" grip in front, and the "cornering response" grip in the rear.

The best case often seems to be to run 255 front and 265 rear (generalizing a bit here on wheel width), but 265's are hard to find.

So, what do you think about using staggered wheel widths with the same tire width front&back?

 

I have some 17x9.5 +40 And 17x8.5 +30 TE37s and with 255/40-17 tires I preferred the wider wheel in the front for all the reasons you mentioned.

Better turn in/steering response
more front traction in turns, so less understeer
better rear traction accelerating with rounder relaxed sidewall
And the +40 offset is closer to stock +50 so less tramlining.

I personally decided stagger is dumb on a car like the FD that can fit just as much wheel and tire up front as in back- but I understand opinions vary...

 

My wheels are Enkie Racing PF01 18X9 +42 front and 18X9.5 + 45 rear wheels.
My tires are Yokohama AD08R, front 255/35-18 at 30 psi, rear 285/30-18 at 26 psi.
At 400+ rwhp, more traction is needed.

 

i like to start with what Mazda did, they built the car after all. Mazda in general runs a 195 tire on a 6" wheel, 205 on a 7" wheel, 225 on an 8" wheel and so forth. this seems to be the happy spot. performance gets worse (or does not improve) if you put a wider tire on, if you go narrower, its slightly better, but it helps if you have a tire that is wide for its size. for example a 205 Hoosier and a 225 Toyo are the same actual width...

this is probably less critical in the rear, if you need more rubber under there.

we tried this on a race car (a miata) and we ended up with 205 tires on a 9" wheel. 225's would have been better, but would have bumped us up a class, its racing, we dynoed like 8 times to try and make less power

 

I like stretched tires on my wheels. I run 11.5” front and back with 285/30/18.

i think an 11” wheel would be good too.

wider wheels provide more ultimate grip in the corners at expense of straight line grip.

 

Overall I feel the benefits don't beat the cons. Staggered costs more overall, compromises grip, and is there for style points to say your car has sooo much power it needs a wider rear wheel.

You can't really rotate tires if your gonna be on the street and/or maximize economy to fun ratio if your gonna track/auto cross(unless your sponsored then who cares do what makes you win) The better driver is often the one with the most track time, if you can't afford to go your skills will suffer.

Under steer is always slower than over steer. Also if you can't keep the power down you either need better tires or what most people need, Driver mod, don't just stab the throttle ease into it your tires/wallet will thank you.
Most people I know over-drive their cars, which is fun, don't get me wrong but your torturing those tires. Also your gonna run out of talent eventually. I only really consider kart tracks/autocross to be where you might honestly have to overdrive and be aggressive because going wide ISN'T an option. (maybe less so on autocross)

I do love BLUE TII's method actually! Kinda the best of both worlds, add a 17inch tire in the rear for even more sidewall and you probably got yourself a gripped up FD. Although I might be worried about snap over steer at that point.
I also share his view on why not fit bigger tires if you can there's no reason not to.(besides cost)

I'm contemplating actually picking up some RPF01's(I know I know) in 17x10+38 and going for a 255 square setup on RE71's. It gives me sidewall comfort on the street, Fairly decent turn in response due to a slightly stretched tire and If I slide my rear end I'm probably going too fast anyway.

I figure if I want to be a little more serious I'll slap on a pair of Hoosiers in 295 or check out some R888R's (275's wheel height at 25.7 makes me nervous for clearance...)

Drag racing and or stop light racing though you might as well just get wider rear wheels and who cares about the front your trying to go straight anyway.

 

JuSanBee,

So much misinformation or is it resentment?

The suggested rim size for RE71Rs in 255/40R17s is 8.5-10 inches. Your 11" would over stretch them as the mid point is 9.25".
Are you one of those ricers?

 

I read this and was immediately confused. Read the post again please. 17x10 that means 10 inches wide. That's within the range and should give a flush look and no sidewall bulge.(can I say hella steering response)
Although I like where your thinking, maybe I should suck it up and go 18x11 and fit a bigger tire. You can't get 17x11 RPF01 If I could I would and I wouldn't be running 255. (now who's spreading misinformation)

Why would I have resentment in a hobby? As far as misinformation it's what I've observed and have no intention of leading anyone astray.
I'm more than willing to argue my point in controlling your vehicles power output to match available grip based on the situation. ie drag,street,track,etc.

Maybe I am rice what do you care? You gonna pay me to not be? Also the 90's called they want their stupid insult back.

Please read before you fly off the handle and be a total dick.If you got something you can teach us feel free. If not and you want a big ole internet flame-war feel free to PM me.

Edit:
After reading the whole post myself I see that you think I'm attacking you. I'm sorry. I didn't mean to come off that way, however I do think you could benefit from more sidewall and more front wheel. I don't exactly know what build direction your going in tbh and I think you'd appreciate more tire up front too.

 

I've ran a staggered set up and the stock sized square set up and while the stock square set up had less straight line grip, it made the car handle a million times better than the staggered garbage set up I had. 18x8.5 in the front and 18x10 in the rear with tires to accomodate. (It's been a couple years since that set up so I don't remember the specs perfectly). I personally believe that there are a few ways to tackle the subject and that is simply, what is the purpose of the car? I like being able to rotate tires if needed on square set ups and the neutral handling that it gives, but then we run in to an issue when we start modding the engine...Torque... The torque makes it so we need more rear grip and wider tires are the easiest way to get this. So if you run staggered, there are other ways to get your good handling back so you stop under steering like a pig. Sway bars, toe, coilover adjusting and the list goes on. Personally, I rather run a 17x9 square set up and call it a day for simplicity and to limit torque since my car is mainly street with the occasional track time and corner handling to me is a lot more important than straight line speed. It's all about compromises essentially.

 

I've owned FDs since 1998 and have been through many different wheel & tire combinations. For a higher-powered FD (say 400-500 rwhp) I like a slight stagger.

Works well for what I like to do with the car, and IMO looks fantastic too. Here's my 'go-to' fitment, 18x9.5 and 18x10 with 255/35 and 265/35 tire. Get the right rubber and you'll have enough grip for 500 to the ground, and you're almost keeping a stock-ish OD in the rear, spot on in the front. I do run 4.33 final drive which helps mitigate the slightly taller rear OD (25.3 inch vs 25). For a more stock-ish car you've got options, on my Montego Blue I'm looking hard at the Sakebomb Garage RZ+ which are a nice square 17x9.5 plus 45. Run 255/40 at each corner and run a 10mm spacer in the rear to cheat and 'stagger' your square fitment

 

just to put something here, I have stock RZ 17x8 and 17x8.5 wheels with 245 and 255 tires.

 

Square 17x9.5 +44 or +45 with 255's is what I'm leaning towards. The car should hopefully soon make high 300s -- I'm thinking 9.5 in the rear is probably adequate at that power level. Another option would be square 17x10, but that might just be adding unnecessary unsprung weight.

I'm also thinking about possibly doing 9.5's +48 all around with 8mm spacers in the rear to add negative offset, instead of splitting the difference with +44 or +45 and no spacers. I don't really recall hearing of others doing that, but it seems to make sense...

 

Here's a good read on tire width to wheel width ratios: https://motoiq.com/how-to-properly-s...performance/2/

Some takeaways:

1. Manufacturer listed tire widths are inconsistent and vary compared to independent measurements.

2. When sizing a wheel for a desired tire size, having a tread width equal to or slightly smaller than your wheel width seems to be the sweet spot for handling and feel.

But most of us don't have the luxury of picking their ideal wheel size, and compromises are made.

Also, if you dig deep enough with this tire stuff I think you'll find most of the guidance you recieve is highly suspect and even the best advice will send you in circles.

Tire specifications in relation to chassis tuning is so totally outside the scope of what most people can comment on. In almost every case you are just getting someone's best guess at why their car is doing what they think it's doing. Don't even take that article I linked at face value.

 

very few people know how tires work. we actually got to talk to a real race tire engineer, and he talked in riddles, but learned a lot!

 

Does a 10 mm spacer fit on stuck wheel lug studs? Are they long enough for 10 mm?

 

I’m wondering about making cutouts in the wheels for the stock bolts to hide in with 15mm spacers. Is it safe to just drill 5x ~15mm cutouts in the back of a wheel?

 

JD here, reading the tire wheel fitment with interest. I have a 93FD that has bee converted to track status by Banzai Racing and the car has seen zero track days due in part to the current Covid situation. My question goes to tire and wheel fitment. Previous, I had a Honda S2000 and here is what I ran for wheels and tires: Enkei PFO1 stagger fit with a 17 x 8" wheel up front and a 17 x 9" wheel in the back. Dunlop Direzza DZII tires. Ran in Nasa and a lot of the guys ran performance street vs. slicks cause they did. my second set of tires were on Enkei RPF wheels. same size tires, but BF Goodie slicks 255/40 17 rear and 225 /35 17 front; but compared to the other set were radically different for width & performance. Now, I have no idea where the car is for horse power, but I know I do not want to run with the PFO1 wheel. I want wide and am wondering if I can run with a 275 or up to 295 in the rear and a 245 to 255 in the front. To be honest, I don't know what I am doing and am looking for some advice. Don't respond and tell me I am an idiot-I already know that. I am just a weekend warrior tying to have some fun. Advise please.

 

18x10 +50 with 285/30-18 front and rear has been the standard track wheel and tire fitment for FDs in the usa for the last 15 or so years.

If you are willing to roll the front fenders you can do 18x11 +45 with 295/30-18 front and rear as I do.

The issue with wider than 295 front tires is actually the tire height. You get to where you have to remove the fender liners and modify the headlight buckets if the tire is much over 25" diameter.

There are a few shorter wider tires that will fit up front like NT01 315/30-18 that is 25.35" diameter. Right at limit of stock rolled front fenders with liners, mudflaps, sideskirts-whatever.

 

My prior FD, this is what I ran as well. 18x10s on all 4 corners with 285/30/18 tires. It was like glue.

 

Thanks for the replies. Can you tell me whose wheels you are using? 18 x 10 is wheel size, what does the +50 mean?

How about some direction for alignment and suspension set up? Just put Olins all around but have a standard street alignment as the engine is freshly re-built and I put 1400 miles on for break in mileage.

 

Damn.. Rich, I really dig those wheels. One of the best looking wheels imo.

 

+50 is the wheels offset.

Stock is +50, so that is what the suspension/steering was engineered to work best with. Closer you stay to +50 the better for handling.

Only reason to go +45 offset with the wider 18x11 with 295 is there isnt enough room on the inside of the fender well.

The old school FD wheels were CCW, but they are expensive and actually fairly heavy.

These days you can use modern Mustang aftermarket wheels or Forgestars like I do for a cheaper alternative.

For track driving you will need camber. The more aggressively you drive, the more camber you will need- so just get out there with a temp probe pyrometer and dial in camber that way.
I would start with 1.5deg to 2 deg up front and as little as you can in the rear for a starting point and go from there.

 

@johnd08
Are you doing HPDE with NASA or are you running their Time Trials or racing?
If you are doing TT or racing, read the rule book where it will probably state the max tire size allowed in the class. If you are doing HPDE, you can do whatever you want.

Furthermore, I'd call Banzai and ask them for a ball park of what HP your car will be making at the boost level you intend to run on track. That will also give you an idea of how wide the tires should be. If you are only around 300 rwhp, I don't think you really need much bigger than a 255 or 265 for example and you'll probably want the 285 if you are planning to run 400 - maybe even 350 and up.