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ZX Autocross Wheel/Tire?


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I'm currently running my 80ZX in BSP. I've got the Tokiko HPs & Springs with a 1 1/8" ST bar on the front. I'm currently running Khumo V710 225/50-14's on my 14X6 6-spoke wheels. This is the second season on these tires and I'm looking ahead to next year when I will probably need to replace the tires. At that time I want to upgrade. At present, I have no additional plans to do any additional work on the suspension. I've spent alot of time reading through the archives and have seen info for the S30 cars with recommendations for 225/50-16's, 225/40-17's on a 17"x7.5" rim, & 245/45-17's on a 17"x8" rim. Are these valid reccommendations for the ZX? I want to stay away from rolling the fender lips, but I'm not going to discount it. For the street, I plan on running a stock wheel/tire combo for now.

 

Also, a recommendation from a fellow autocrosser was to consider going with a 13"tire on 7", 8", or 9" rim from Diamond Racing Wheels. I know some of the CSP Miata's run this type of set up rather successfully. Any thoughts with going with the smaller wheel set up?

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I believe BSP allows for fender rolling but no flares and aftermarket springs but no coil overs, I don't think you can fit a 13 wheel over your stock brakes, but the smaller diamter is gine if you need the extra gear advantage, the problem is if you find yourself at the top of secone gear a lot now, you might find the smaller diameter wheel forces you to do mroe thrid gear up and down shifting

 

wiuth larger diamter wheels you are adding upsrung weight, which can slow you down if you feel you are short on power now it will get worse

 

I'd think a 16 x 9 could be made to fit and offers additional width at a size where tires that can use that width are avaialve, you won't find any 265 tires in a 14 or 15 diameter

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Take a look at the MSA 2008 Nationals Photos in the AutoX section.

There are photos of Frank280ZX's 79 ZX running the 13X8 Diamond Wheels. The thing took 5th fastest time of the day running cut 2+2 springs, Illuminas, stock sway bars and stock drivetrain with a stripped interior. It was LOW and STUCK LIKE GLUE!

 

It's the white car with the John Coffe FRP Hood (black) that cost more than the car and parts did combined!

 

I would recommend the 13X8 with some good slicks. They cleared the brakes fine, and with the Portefield R4S pads they would pull you up out of the seat on braking!

 

The gear ratio advantage you get makes the stock gearset nice. You will be in second/third and sometimes even 4th on faster courses! Frank was really happy with the setup.

 

No flares, no coil overs, and if he had the MSA Swaybars on that thing the body lean you see in those photos would be gone!

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Tony let me correct you on one front . It has KYB gas struts, not the tockico's :) AND its a 78 not a 79 :P

 

anyhow they where a blast .. i was really happy and sad that this year the tires where gone ...

 

 

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They clear the stock brakes.

Hence the car had no sway bars or poly bushings, so you will have the benefit of those too!

 

one more

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This year i ran 15x8 with the cheapest tires they had, a 400 tread wear is something else considering the gumballs had a 40 tread wear :(

But i did ad the MSA sway bars, even though i did not hook the way the 13's did there is a big difference there !! i cant wait for the poly bushings to go in :)

 

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Id say either the 13" or go to La Habra and buy the wheels seen above. Problem is that they are fairly heavy (16lbs a wheel verified by mister JohnC) but with some 225 slicks.

You cant beat the prize $350 for the set of four! (or shipped off ebay!! asyou seem to be in Maryland. Check ebay SG motoring)

 

I hop to be running the white turd at Spa Belgium in July on slicks on the same 15x8 rims, just as a shake down to see what needs to be done to turn in it into a real racer.

 

For now I’m still leaning towards the 13" especially for autox. The big advantage is that you will reduce your gear ratio, so it will compensate the lack of power.

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I've already got the Portfield RS4's per Tony's recommendation before. Forgot to add that in the original post.

 

Tire brand? Khumo V710's come in a 215/50R13 and will fit a rim of 6"-7.5". Hoosier A6's come in a 225/45ZR13 - 7"-8.5" rim, 225/50ZR13 - 6"-8" rim & 255/40ZR13 - 8.5"-10" rim. Not sure of the longevity of the A6's, but the V710's seem like they will go twice as long as the previous tire to the A6's. I can't remember the model tire. Frank, what are you running on your 13's?

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I've already got the Portfield RS4's per Tony's recommendation before. Forgot to add that in the original post.

 

Tire brand? Khumo V710's come in a 215/50R13 and will fit a rim of 6"-7.5". Hoosier A6's come in a 225/45ZR13 - 7"-8.5" rim, 225/50ZR13 - 6"-8" rim & 255/40ZR13 - 8.5"-10" rim. Not sure of the longevity of the A6's, but the V710's seem like they will go twice as long as the previous tire to the A6's. I can't remember the model tire. Frank, what are you running on your 13's?

 

 

I have no clue i think it where hosiers of some kind.

I borrowed them off Ian Stewart, like i said the car pulled from the line.

Due the fact of the small tires my diff 'ratio' was somewhere around 4.8, it slammed the car to the ground giving a good low point of weight.

The only problem I would see is your front valance hitting the ground under cornering or braking

Tony might know the tire brand though.

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Thanks Frank! I'll check back later and see what Tony has to say.

 

Just looked at the spec sheet. My current set up on the 14x6 rims is 22.8" in diameter which just shy of 2" lower than stock. The 13" set up is 21.5" on the V710's and 20.9" - 21.9" on the A6's. I'll keep the front valance in mind especially once I get the MSA stage 2 body kit installed later this year. The air dam in the current picture is currently stored in the loft in 3 pieces due to excessive cone carnage last year.

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Great to see someone going smaller. In addition to lower gear ratio you also lower the cg and even if the wheels are slightly heavier, the moment arm is shorter. If they're way heavier then obviously to optimize lighter wheels would be a good idea. Brake clearance is obviously not an issue, but just for clarity the reason why is because the fronts are 10.5" vented rotors instead of the 11" solid rotors the Z has. Even the Z can fit 13" rims with a little bit of caliper grinding. Good job Frank coming in 5th overall in stockish ZX (bet that surprised a lot of people), and thanks for proving the point I've tried so hard to make over the years.

 

If you go Prepared you can run real slicks too, and there are lots of choices for 13's. Used slicks are available and cheap. Used DOT's are hard to find.

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Well 5th note that it is an driving school, not really a as sharp measured event as a real Solo2. I think John turned a few fast laps in his 350z aswel, they where not on the time list of the day. Anyway i was fast enough, and had a blast.

I had two solo2 prepped cars behind me..

 

What it shows?:

Power can work against you

The more suspension setting available, the more 'wrong' settings you have.

 

The 13's where very light, as they where a steel wheel .. The 15x8 SG motoring wheels are 16lbs.. so not light by long shot..

 

The wheels really surprised me.. the way it woke up the car, and the way it glued to the ground !!.. there is something to say for the 13" that i would never have discovered if I hadn’t tried.

The ZX is a stock 238K mile 78, but with an gutted interior, KYB shocks, cut 2+2 springs, and new ball joits and rods.

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I believe BSP allows for fender rolling but no flares and aftermarket springs but no coil overs,

 

Not true. Flares and coil overs are perfectly legal in BSP.

 

A 15 x 8 wheel with 225/50-15s would work very well on your 280ZX. If you're willing to flare the car and run coil overs, a 15 x 10 wheel with the Hoosier A6 275/30-15 would really work.

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Not true. Flares and coil overs are perfectly legal in BSP.

 

A 15 x 8 wheel with 225/50-15s would work very well on your 280ZX. If you're willing to flare the car and run coil overs, a 15 x 10 wheel with the Hoosier A6 275/30-15 would really work.

 

you are of course correct, I never ran bsp, just going by what I've seen in local bsp cars, it's odd that stock has to run stock rprings, and I know prepared can run coils but i would have thougth sp would be a middle ground, guess not

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With Solo2 the names of the categories are misleading. There's no intended progression from Stock to ST, to SP, etc.

 

True enough! I added the springs and Bang! From E stock to BSP with the C4 Corvettes, 911's & Subi's.

 

I'm leaning toward the 13's, but will continue to run the 14's through this season. I've got a lot of operator head space that needs adjusting. This past weekend was a grim reminder. Post action report to follow once official results get posted. Tin worm gets the attention this summer along with a paint job, but I want to start getting my ducks in order now so I can jump on an opportunity if it avails itself.

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With Solo2 the names of the categories are misleading. There's no intended progression from Stock to ST, to SP, etc.

The st and many other modern classes were added to fit more popular mods found on tadays cars. My understanding was that the natural order of progression was: stock, street prepared, prepared, modified. Each class allows mods from the lesser classes plus it's own. The st, sm classes were drawn form what the SEB thought would fit popular mods found on modern cars

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Tony let me correct you on one front . It has KYB gas struts, not the tockico's :) AND its a 78 not a 79 :P

 

'78 280ZX?

 

 

Personally, I'm a fan of staying with small-diameter wheels rather than having to deal with the higher ride-height and gearing associated with taller wheels.

 

If I were to make a change, I think I'd go 255/40ZR13 Hoosier A6's :)

 

Hmmm, I gotta look into that...

 

Who makes a 13x9 wheel that weighs and costs next to nothing?!

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