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wheel/tire choice for FC track car

Old 08-06-16, 07:30 AM
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wheel/tire choice for FC track car

What wheel and tire sizes do you guys use for track driving?

Would an 17" wheel with a "40" sidewall be better then an 18" wheel with "35" sidewall? Or the "35" better then the "40"?

So, for example, 245/40r17 or 245/35r18?


And if the tire is slightly wider then the wheel, for example, a 245 tire on 8J (instead of 8.5), would that have any influence on the amount of grip?
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Old 08-06-16, 09:24 AM
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Generally, a 17" setup will be lighter than the 18" variety. Having a little bit more sidewall can help with straight line grip and make the tires more predictable in turns.

This article gives a decent idea of what to look for.

How to PROPERLY select and size TIRES for PERFORMANCE > MotoIQ - Automotive Tech, Project Cars, Performance & Motorsports

You want your tires to be flush, or slightly narrower than your wheels, depending on application.
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Old 08-06-16, 10:28 AM
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That is interesting and confusing at the same time.

I currently have 225/45r17 falken azenis on 7.5J rims and ordered new toyo's in the same size.

But according to his story and the sizes shown on tirerack.com, the 225/45r17 r888 tire should be best on a 8.5J rim. Or even better, 225/40r18 on 18x8.5.

And when I expected to put a 275 tire on a 9.5J rim, according to the list it should be a 255 tire for that rim.


this is how the 255 falken looks on a 8.5J wheel



I didn't see this comming to be honest but I must say, the story makes sence. But I do see different things sometimes. Like toyo's that slightly buldge outwards. Looks cool, but I understand it makes the car a bit floaty if it realy is "to" wide.

Only thing that I didn't see in the story, is a bit about the sidewall hight.

But it is lots of info to think about.

thanks for the imput!
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Old 08-06-16, 10:57 AM
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I would say for a 8.5 wheel, you should be looking at 235/245 section width. I personally am a big fan of meaty tires on wheels for the looks alone, but I'm under the impression that you are asking about functionality and performance over form.
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Old 08-06-16, 11:39 AM
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Thanks, but I do agree with you on the looks. But a stanced car with a bit strecht can look cool aswell.

To get back at the sizes, I looked at toyo's website, they advice the 225/45r17 tire to be mounted on a 7.00, 7.50 and 8.50 rim. Having a threath width of 8.7, it could confirm what is said in the story although you would say a 9J rim might give better performance.



How ever, "7.50" is made bold on their site, making me guess that that is their advice.
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Old 08-06-16, 12:35 PM
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we've never done a side wall height comparison, so i don''t have a lot to offer there, but we have done a wheel width to tire width test, or testing.

Mazda's rule of thumb, is to put a 205 on a 7" wheel, 225 on an 8" wheel, and 245 on a 9" wheel (etc), and this is pretty close to optimal, actually.

we started with a 225 on a 7" wheel and then went to an 8" wheel, and then a 9" wheel, the 9" wheel performs the best. given our 45 side wall. due to the rules the next step was a 205 on a 9" wheel, and that works too.

the other thing we know to be true is that a shorter tire helps gearing, and with an FC, there is an upper limit to tire diameter before you just run out of room.

the 225' you just ordered will be fine, but that same tire would be better on a wider wheel. or conversely, a 205 on your 7.5" wheels is about right
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Old 08-06-16, 12:51 PM
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Nice, thanks!

I am still not sure whether to go for 17", or 18". But you guys gave me loads of new (to me) intel on tire width compared to rim width and I will surely keep that in mind on the new setup.

If I choose to go with a new set of 17's, I would be able to use the 225's I just ordered and experience this my self. But that's only "if".
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Old 08-07-16, 01:09 PM
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If you want the best performance you buy the smallest diameter wheel that will fit over your brakes. There are SOOOOO many reasons why.

18"s on an FC are nonsense (even aesthetically, for the street if you want my 2 cents). I run 15" rims with 205s or 225s both 50 sidewall depending on what class im running the car in.

17" rims look great on street cars but the overall package will likely be heavier and you just end up spending more on tires. Not to mention ride quality exponentially suffers as you go smaller sidewall.

On the track, lower profile tires limit your ability to tune the overall springrate and contact patch of the car using tire pressures.

Larger profile also provides less risk of rim damage. The only reason to run larger rims (aside from maybe you already have them) is to fit over larger brakes. There are NO advantages to oversize rims with how modern tires perform.

I could dive further into the asthetics issue for street cars....but i'm quite sure that does not address your original post at all....mainly i think cars and trucks with big rims that have all this empty space between stock size brakes and the inside of the rim look way worse than just getting the smallest diameter rim for the brakes. Rant-off...

Last edited by RockLobster; 08-07-16 at 01:17 PM.
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Old 08-07-16, 01:36 PM
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Originally Posted by RockLobster View Post
If you want the best performance you buy the smallest diameter wheel that will fit over your brakes. There are SOOOOO many reasons why.

18"s on an FC are nonsense (even aesthetically, for the street if you want my 2 cents). I run 15" rims with 205s or 225s both 50 sidewall depending on what class im running the car in.

17" rims look great on street cars but the overall package will likely be heavier and you just end up spending more on tires. Not to mention ride quality exponentially suffers as you go smaller sidewall.

On the track, lower profile tires limit your ability to tune the overall springrate and contact patch of the car using tire pressures.

Larger profile also provides less risk of rim damage. The only reason to run larger rims (aside from maybe you already have them) is to fit over larger brakes. There are NO advantages to oversize rims with how modern tires perform.

I could dive further into the asthetics issue for street cars....but i'm quite sure that does not address your original post at all....mainly i think cars and trucks with big rims that have all this empty space between stock size brakes and the inside of the rim look way worse than just getting the smallest diameter rim for the brakes. Rant-off...
I agree with you here, but I have been finding that it can get tougher to find tires in 15 and 16 inch sizes at times. I worked for a tire company for a few years and with the influx of new cars with factory fitted 17s, 18s, and even 20s. We were running out of performance tires in certain sizes.

My Dodge SRT4 ACR took 225/45R16 tires and there are a paltry few options in that size, but when I upsized with 225/45R17 tires that came on the standard SRT4, the options grew exponentially. This is one pathetic example, but I have seen first hand that the 17 and 18 market has gotten huge.

I did also find out that 17s on my Dodge are heavy as hell compared to my old setup. Probably because my old setup had BFG tires on BBS rims, vs my current Federal tires on OZ Wheels. The Federals are terrible tires, but I got them for free.

On an FC, it does seem like the size with the most options is the 225/50R16 and wider sizes. I personally like the aesthetic look of the 17s, but I'm not racing my car at this point.
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Old 08-07-16, 02:04 PM
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You're absolutely right concerning anything made for the street. Race tires are readily available in those sizes.

Some of the "streetable competition tires" start at 19"....which i think is bonkers. The street tire choices for my M4 @ 255/40R18 and 275/40R18 are astonishingly slim. But if i had 19" rims and was shoping 35 sidewall tires i'd have dozens more choices.

The main reason is of course because any performance oriented car or truck made in the last 10 years has monster brakes, requiring those size tires.

Plus people seem to love having huge rims...even at the expense of ride quality...

Last edited by RockLobster; 08-07-16 at 02:23 PM.
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Old 08-07-16, 02:16 PM
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I never took too much time to look into race tires because I simply had no need, but I did find just scores of semi slick and race slick 225/45R16, but only two or three tires in the street compound. The company I worked for had actually discontinued my size in their brand, so I was unable to get the sweet employee discount.


It is amazing at the size of brakes and tires on factory cars now. Even a simple Corolla gets 17s standard. I remember when 15s were and upgrade and 17 was reserved for Euros only,
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Old 08-07-16, 02:24 PM
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Some of it's necessary and some totally unecessary.

I had to laugh when i was building a potential replacement on Toyota's website for my Turnda. I will have to buy the TRD off road package just to "upgrade" to 18" rims from the 20", which are standard...lol
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Old 08-07-16, 03:29 PM
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GeenIdee


wheel/tire choice for FC track car
What wheel and tire sizes do you guys use for track driving?


You need to decide what class and racing organization you will be running in before you can choose wheels/tires for a track car.

Wheels and tires are the first decision you make when building a race car and all design elements of the car follow from this choice.

If your wheels and tires are unlimited... you are in for a world of hurt LOL.
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Old 08-08-16, 04:07 PM
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I do not do any competition driving with it, so my wheel / tire choice is free.
The difference in costs between 17 and 18" is not that much, I personaly dont see that as an issue.
I don't care a single bit about ride quality. Track car's are just not meant to have a great ride quality ^^
And I will fit a BBK sooner or later and therefore 17" will be the minimum.

The rim must fit well, it must fit a BBK, it must be lightweight, it must fit the tire that will give the best performance.

I've already found an option for 18". The rear wheels I had planned are 8KG, front even lighter. But so far I'm struggling to find a decent or good looking 17". Except for the Work TE37 but the rays website confuses me a bit. Not sure if it's up to date etc.

Last edited by GeenIdee; 08-08-16 at 04:10 PM.
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Old 08-08-16, 04:47 PM
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I do not do any competition driving with it

Excellent, then you just need a set-up with cheap tires that have nice track driving habits.

I would go with 17x9 (+25 to +35 offset) front and rear with $99 Federal 245/40-17 595-RSR tires.

If you go with 17" TE37 I know from my cars/wheels that you can fit a 14" rotor big brake kit on them.

Mine are TE37 are 17x8.5 +30 Front and 17x9.5 +40 Rear and even the old '90s flat spoke forging (because that is what I could find used).

Here is a chart for TE37 current offsets from Ray's

https://www.rayswheels.co.jp/product...n&wheel=TE37SL

I wouldn't do 18" unless you plan on widebody the car to be able to fit wider than 255mm or so tires. The extra tire height on available wide 18" tires will keep you from getting the car low.

Edit- so for new TE37s I would use the 17x9 +22 front and rear or the 17x9.5 +28 front and rear

Last edited by BLUE TII; 08-08-16 at 04:51 PM.
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Old 08-08-16, 04:52 PM
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Originally Posted by BLUE TII View Post
I do not do any competition driving with it

Excellent, then you just need a set-up with cheap tires that have nice track driving habits.

I would go with 17x9 (+25 to +35 offset) front and rear with $99 Federal 245/40-17 595-RSR tires.

If you go with 17" TE37 I know from my cars/wheels that you can fit a 14" rotor big brake kit on them.

Mine are TE37 are 17x8.5 +30 Front and 17x9.5 +40 Rear and even the old '90s flat spoke forging (because that is what I could find used).

Here is a chart for TE37 current offsets from Ray's

https://www.rayswheels.co.jp/product...n&wheel=TE37SL

I wouldn't do 18" unless you plan on widebody the car to be able to fit wider than 255mm or so tires. The extra tire height on available wide 18" tires will keep you from getting the car low.
I would do this.
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Old 08-08-16, 05:02 PM
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Good advice above. I would personally never go less than a 40 sidewall for a track tire. Less risk of rim damage, better tuning ability using tire pressures, etc, etc

I've always had good luck with Enkei RACING wheels or team dynamics, and good god they are way less money than work/rays.

Team dynamics are semi customizable in offset and width. They are special order in many cases.

Why spend $300-500 per wheel (or more) when you can spend around $150 per. Hell thats at LEAST one set of extra tires!

I tend to look at car expenditures in denominations of hoosier tires these days. ;

Plus when you damage a wheel going off track it's less of a hit there as well.

Last edited by RockLobster; 08-08-16 at 05:14 PM.
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Old 08-08-16, 05:49 PM
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You can always look at the tried and true Enkei RPF1 wheels. They come in 17x9 +22
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Old 08-11-16, 01:29 PM
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Just got a fresh set of 225 toyo's on today. They looks pretty big on a 7.5J wheel. But I had to, for now.


Everything did got me thinking, and i'm not finished with that just yet (imagine the headaches every day).

Staying on 17" would mean that I can re-use my tires as they have the size I would put on the new wheels.

My original plan was to go with rear wide fenders, and get the rear wheels sitting a bit wider. The thing is though, I had wedssports on my mind and with 18" the offset was pretty much right.

Going to 17s with those wheels will mean that over fenders are no longer needed because of the offset those 17x9.5's have. 9.5 with original fenders do look a bit tight on paper, Altough, it seems that @Blue TII has them on there so I guess it should be fine.


So, anyway, i've got loads of new info, thanks for that guys.

I'll go try and decide what I want to do.

@Rocklobster, Altough you are right, I'm not looking to do things as cheap as possible. Not looking to do it expensive either but do have an expensive taste. Not to mention I can't back down after the work I already did lol.

Last edited by GeenIdee; 08-11-16 at 01:31 PM.
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Old 08-11-16, 02:52 PM
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9.5" wide is tight up front with a 255/40-17 on an FC.

You have to have struts with longer arms/big 60mm tube and a slotted upper hub mount. Then you lean the hub to max positive camber and dial in the negative camber you want at the strut top mount as usual.

I know Scrap FC did this and fit his 17x9 +35 255/40-17 up front with no spacer on rolled fenders with room on outside for wider wheel. Drove great.

Because of this we know he could have run 17x9.5 +28 up front with 255/40-17 (same fitment inside to strut, sticks out 14mm at wheel and sticks out 7mm further at top outside tire tread).

Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit
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Old 09-20-16, 11:49 AM
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I got a 9.5 +38 RPF1 to fit in the front with a 255/40/17 RS2 with -2.75 degrees of camber, a couple small spacers, and a front fender roll on stock front fenders.






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Old 09-20-16, 11:53 AM
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I'm going to 10.5s with 275s under Shine front fenders now.





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Old 01-23-17, 11:27 AM
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Are you guys cutting your strut tower to allow more camber adjustment to reach those camber numbers? I have some 17x9 +25 wheels with a 10mm spacer and 245 tires and I'm having to push the upper slotted bolt hole on the coilover hub mount inwards to get over 2 deg of camber. This puts the wheel really close to the spring on my coilovers though
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Old 01-23-17, 12:20 PM
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On my old Stance XR I had to machine the slots further in the aluminum upper mount so the strut shaft nut was right against the stock sheetmetal hole lip.

That got me to about -5 camber.




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Old 01-23-17, 01:02 PM
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I'm doing the same thing with my coilovers.

My 275 tire will touch the spring if I go all the way in with it on the strut mount, but I had the slots cut longer in the camber plate so I use a combination of both adjustments.
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