Best wheel/tire size for 2nd Gen
 

I'm picking up my 86 FC Thursday, its going to be purely an AutoX/DE car, although I will be driving it to events and to Goodberrys on Saturdays ;-). It's bone stock and I don't have the cash to transform it into a supercar immediately, so I'm just doing some mild suspension mods first. I am having Tokicos and Eibachs installed before I even drive home. I plan on getting some diamond race wheels and stickies for it next thing. I have no idea what will fit though. Since I'm setting up for CSP tires and wheels are open, so I want the best size I can fit without anything more than mild fender rolling or hopefully no rolling at all. What sizes are people running that perform well? 15s, 16s or 17s? What width? BTW its 4 lug, for now anyway.

Thanks!

Alan C.

You can get a 5 lug conversion cheap, that should be a first mod, then get some wheels that way you wont wind up with a set of 4 lug wheels you can get rid of.

But 15-16's would prob be best, and like 8wide in the front and 8 in the rear, nine if you want to, and they will fit without fender problems.

-Chris

I was thinking about the 5 lug conversion, but I've had two racers tell me the smaller brakes are adequate and the less unsprung weight is desirable. One even said if he was going to start over building a car he would go with the four lug! Comments?

Thanks for the reply!

I agree with Chris-ReedTN, five lug conversion might be a good move for getting rid of wheels later on if you go into this thinking that you are going to be upgrading later. As far as what you have now, you might be ok with even 14" wheels and tires on 4-lugs. (Sorry if this is incorrect about the 14" thinking of the phone dial wheels, more familiar with FB than FC). Better gearing and less rotational weight with the 14" that should still fit over stock brakes. This is really important on AutoX course. Of course, if this is a daily driver/AutoX car, the speedo will be off, so on the street just need to know how much to correct. My suggestion for cheap, good wheels and tires is Kosei R1's, Kumho Ecsta AutoX tires. Light weight, good prices, strong wheels, durable tires. For now this will exploit as much potential as you can expect with given suspension mods. Plus easy to move later on, such as to a Spec Miata racer or some other FC racer, should you decide to go even bigger.

The car has aftermarket 15s on it now, although its still 4 lug. Thats kind of why I was thinking of keeping it 4 lug for a while, if I converted it now I'd have to buy 2 sets of wheels, 1 for street tires and 1 for stickies. Then again I just could leave the kumhos on it full time. I'll probably get Kumho Victoracers, thats what all the guys around here run, supposedly a good blend of grip and wear rate. I've always autocrossed on street tires, except for once in a Mustang on Hoosiers. BIG difference.

Whats the best (cheapest ;) way to do the conversion? I just need to find a junked car and take the hubs/calipers? Axles too? Of course then I'll want an LSD! The list goes on...

Thanks for the helpful replies.

Alan C.

I would certainly spend the money to do a coil over and camber plate setup rather then sport springs. Spend a little more now to not waste your money on stuff that you will upgrade later.
If you can find a used set of race tires to fit on your stock wheels (Neons maybe)you will be able to invest more into things that will matter more then 5 lug and the bigger brakes it brings.
Usually after Nationals people will have tires for sale that they have almost used up and will usually get rid of very cheap.
Best of luck.

I can say that the 4 lug cars CAN be as competitive. the local SFR SCCA champ ran 4 lug last year.

But the bigger rotors mean more mechanical force, meaning less heat for the same work, meaning less heat in the rotor/pad, meaning reducing pad wear, fade, and rotor wear. Combined with the vented discs in the rear (better cooling, less warpage), and thicker front discs, brake fade is non existant with my ITS car. I nail the brakes and I stop.

Am I giving up some unsprung weight and rotating mass? probably. To me, it's worth the cost to not have to futz with brakes every weekend.

PaulC

17x12s :D

4 Lug Vs 5 Lug/ Wheel and Tyre Size
 

My $.02. I have run a 4 lug car for over 6 years in various race lengths on different tracks. The 4 lug brakes have worked very well with minimal concern. Just keep cold air on the front brakes and the brakes will live with good quality pads. Mine is run for 1 hour at speed ranges from 130 - 30 mph and I normally get 3-4 races on a front set of Hawk Blues. The rears last at least a year.

I would suggest that the decision point you have to make is the type of events you will be attempting. Are you going circuit racing or solo or lapping. For Solo and lapping the brakes work fine and the reduction in unsprung weight will help acceleration and handling (theoretically). For race use bigger brakes are always more reliable but may not provide better braking as this is a function of available tyre grip.

As to wheel size weight and tyre contact patch are most important. I am using 15 x 7 wheels, lightest I can afford, and Toyo RA 1's (spec tyre). I am able to generate over 1.5 g's ( according to on board data logger). Larger wheels and tyres will increase grip at a cost of increased weight and straightline frictional drag.

Excellent info! Just what I was looking for, thanks. It will be some time before I'm wheel to wheel racing. When that time comes - if at all - I may need the bigger brakes for fade resistance since the brakes won't be getting as much air while drafting and/or in traffic (if I understand your comments correctly).

Thanks to everyone else too, lots of informative replies. Guess I'm going to stick with 4 lug 15s for now (also recommended by racers in other forums). Lots of Miatas run 15s, which means lots of cheap used racing tires ;-)

Now I need to think up a suitable name that projects my lofty standards! Hmm... Low Rent Racing? Duct Tape Racing? :p: :D

If you are on a budget and want to do it right..... do the 5 lug upgrade with 4 piston aluminum calipers and vented rotors (front/rear) as most are suggesting. Everything transfers over to the 4lug car in about 1 afternoon. Make sure you get hard and rubber front brake lines with the conversion.

As you plan to AutoX you should try and find some used convertible rims. They are 5 lug BBS style "mesh honeycomb" rims and are 15x6.5". They actually only weigh around 8.5lbs which is pretty awesome as the lightweight '89-91 16x7 units are around 16lbs! Then slap on some quality 225/15's all the way around and you are good to go. If you can afford Bridgestone S-03 tires you can run them on the street and AutoX as they work well. If a race only setup.... get Kumhos (good and not too costly) /Hoosiers (costly..... one of the best for roadracing/Toyo RA-1's (medium cost... good tire).

Get coilovers to begin with. Allows you to fine tune the height and play with camber adjustments etc. I got mine from K2RD.com and like them very much. Price was good too. My car hanldes well now and I look forward to every up and coming corner.

Make sure your car has posi/LSD out back. You are going to need it. To test for this.... jack up the back of the car. Roll one tire and if the opposite side turns in the same direction then you have posi/LSD most likely 99% certain.

A larger front sway bar should be in your budget also.

Good luck,

GNX7

Regarding the unsprung weight "difference" between the FC four lug hubs and their iron calipers vs. the five lug versions with bigger rotors and aluminum calipers, I have personally held both in my hands at the same time and could not come to a conclusion on any weight difference. At least as far as the fronts go, they weigh the same as far as I am concerned; maybe they could have a pound or two difference but my hands couldn't tell; holding both at the same time, switching hands, etc. - if my eyes were closed there would be no way for me to tell which was which.

The rears might be a tad more due to having iron calipers on both types (4 and 5 lug versions) but larger rotors on the 5 lug version. The pads are the same on the rear calipers . . but the base model caliper was smooth sided while the GXL caliper had heatsinks cast into it.

I just finished doing a 5 lug swap myself and am glad I did. There are so many wheels that fit 5x114 lug patterns. I took the advice of turbojeff and will be running 90s era 300zx 16x7.5 wheels with 225-50-16 tires for autocrossing.

Most people can't do this but its best to build your suspension around the tires you plan on running. Certain tires work better with different spring rates and struts. The alignment setting that work good on one type of tire may not work with another type of tire. Do some more research and try to decide which tire you are going to use. That will help narrow your decisions on the suspension.

Where can you find the 5 lug conversion kits at?

If you do go 5 lug, and coilovers, 17x8s with a 235-40-17 will fit nicely. I ran this on my road race car with good results. If this is mainly a DE car, I would suggest Carbotech XPs for brakes in the front, and EBC red, or green in the rear. RA1 is a nice long lasting R compound that will tolerate many more heat cycles than the competition.

We've had good results with 16" rims with 225/50/16's in all 4 corners.&nbsp Going larger rims will most likely mean more weight in the corners - upsprung weight sux!


-Ted

4 lug
 

Mark you TII wheel loving freak!

Best bang for the buck is first gen. Supra wheels, they are 14X7 decently light and plenty tough. Put on some Hawk Blues for track day and I gurantee you will have more stopping power than you need and more than most people with big brake kits and "street performance pads" Hawk Pads are unfadable unless you really have like over 350 usable HP on the track.

Carl-

I hope to test out those 17x8 235/17's RA-1's this November at Sear's Point at my first NASA event. I'm doing the HPDE school and getting into road racing slowly.

My white GN powered RX-7 went to heaven as it was starting to rust and the body was pretty beat up. I'm having the motor refreshened and plan to do another GN powered FC by early Spring '04 and have it running some 9's.

I'll be racing an '87 SE base car at the NASA event. I converted it to 5lug with T2 brakes, T2 rear diff, custom driveshaft, K2RD.com coilovers with AGX shocks, Energy Suspension struts/shocks, and '89 T2 rims with 225'sfront and 245's rear. 225's all the way around would be a better choice as the rear's definately sag over the rim. The car has no c/c, initially was a/c delete, and is a manual rack+pinion car. I'm dying to weigh it and see what it is. HP+ pads and hope they can withstand the corners of Sears Point.

-GNX7

I guess Todd is still logged in on my puter..... maybe I should cause some havoc :).

Time to relog in.

-GNX7