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Discussion Starter #1
Well I will be installing a new clutch and Lightened flywheel this week, which I believe puts me out of STR. So I am looking at R compounds and I'm trying to decide if I should do a 225 square setup, or 225's front and 275's rear. So is 275 too big for the power of the car? (Right now I just have exhaust and intake, and soon Lsd and lightweight flywheel) Also, its alot of stagger, so theoretically it should understeer, so ill probably run little camber in the rear (-1.5?) and more in the front (-3?). I have never run R compound slicks before so I really have no clue, any suggestions?
 

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Well I will be installing a new clutch and Lightened flywheel this week, which I believe puts me out of STR. So I am looking at R compounds and I'm trying to decide if I should do a 225 square setup, or 225's front and 275's rear. So is 275 too big for the power of the car? (Right now I just have exhaust and intake, and soon Lsd and lightweight flywheel) Also, its alot of stagger, so theoretically it should understeer, so ill probably run little camber in the rear (-1.5?) and more in the front (-3?). I have never run R compound slicks before so I really have no clue, any suggestions?
275's on all four corners, -2.5 degrees camber rear, -3-4 degrees camber in front. Tons and tons of spring rate.
 

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It really depends how competitive and how serious you want to take it. Almost all of the CSP miatas run the 275 A6s on 15x10 wheels all around. I'd imagine you'd want to do the same to be truly competitive. I'd look at their setups for guidelines since the miata is a similar power and weight to the spyder. If your just running locally and don't have a competitive/prepped CSP car in your region than I think 225s all around would be fine on 15x9s.
 

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Will 275's fit on the front? I currently have 5k springs front and 7k rear.
They don't really "fit" on the back, either. As far as springs, you'd want to go stiffer to be competitive. And to sawzall the fender wells and convertible top.

225's on 8 or 9" wheels is a good compromise if you're just looking to have silly amounts of fun. I'd do 8" wheels if you don't have adjustable camber plates, since the 9" wheels require lots and lots of camber in front.
 

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Discussion Starter #6
They don't really "fit" on the back, either. As far as springs, you'd want to go stiffer to be competitive. And to sawzall the fender wells and convertible top.

225's on 8 or 9" wheels is a good compromise if you're just looking to have silly amounts of fun. I'd do 8" wheels if you don't have adjustable camber plates, since the 9" wheels require lots and lots of camber in front.
I won't be competing nationally so I'll probably just go with 225's. It's also my DD so stiffer springs wouldn't work out so well. Why do the 9" wheels require more camber in front than the 8's?
 

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I won't be competing nationally so I'll probably just go with 225's. It's also my DD so stiffer springs wouldn't work out so well. Why do the 9" wheels require more camber in front than the 8's?
Clearance issues arise at the fender with most, if not all of the 9" wheels that fit in the front of the car. My 8" wheels with a 36 offset rub and a 225/45R15 tire. just barely on the inner fender lip when they're at -2 degrees camber, which is what I drive to and from events with. A roll would eliminate this. An extra 1/2" of wheel on top of that would put it back into the fender again, unless you camber it even further in to move the top of the tire closer to the strut.

Joel brings up an interesting idea- a 13x9 with some 255's would be another possibility.
 

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Clearance issues arise at the fender with most, if not all of the 9" wheels that fit in the front of the car. My 8" wheels with a 36 offset rub and a 225/45R15 tire. just barely on the inner fender lip when they're at -2 degrees camber, which is what I drive to and from events with. A roll would eliminate this. An extra 1/2" of wheel on top of that would put it back into the fender again, unless you camber it even further in to move the top of the tire closer to the strut.

Joel brings up an interesting idea- a 13x9 with some 255's would be another possibility.
Rubbing depends on your ride height and spring stiffness as well. I autocrossed 15x9 225/45/15s on stock suspension and never rubbed. I then lowered the car roughly 1" in the front but have stiff front springs (500 lb/in)+22mm front swaybar and only -1 camber and never rubbed.
 

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Rubbing depends on your ride height and spring stiffness as well. I autocrossed 15x9 225/45/15s on stock suspension and never rubbed. I then lowered the car roughly 1" in the front but have stiff front springs (500 lb/in)+22mm front swaybar and only -1 camber and never rubbed.
Very True.
 

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Discussion Starter #10
Rubbing depends on your ride height and spring stiffness as well. I autocrossed 15x9 225/45/15s on stock suspension and never rubbed. I then lowered the car roughly 1" in the front but have stiff front springs (500 lb/in)+22mm front swaybar and only -1 camber and never rubbed.
Rubbing shouldn't be a problem with 225's on a 9" wide wheel with my current setup, even if it is, I can raise the ride height. Thanks for all the replies!
 

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I'm late to the party, but fwiw, my opinion is if you aren't running the 275 hoosiers in CSP, there is no reason on this earth not to go 13's. You can pick any width you want for the tires you want to run, set the camber based on performance/tire wear, and not touch the body at all. It is easy to keep the tires off the fenders, even though they stick out. The smaller diameter makes it so you drive to the event with a reasonable ride height, then, without messing with the camber curves, CV joint angles, or anything else, you drop it over an inch just by switching tires. The smaller diameter makes the car feel like it has forced induction compared to stock in first gear. 2nd gear ends up in the meat of the power curve, and 3rd is closer to 2nd, meaning potential for using more area under the HP curve. The shifts aren't as frustrating because they often fit in conveniently with the course, instead of being mid straight needing 3rd, then needing 2nd again before the next element. 13" tires, compound for compound, last about the same amount of time before they cycle out compared to 15's, but cost dramatically less. There is more, but bottom line is CSP spyder needs/is best on 13's if you aren't cutting the fenders with a sawzall. Running STR, I will actually miss the gearing change more than all the other race tire benefits.
 

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Discussion Starter #12
I'm late to the party, but fwiw, my opinion is if you aren't running the 275 hoosiers in CSP, there is no reason on this earth not to go 13's. You can pick any width you want for the tires you want to run, set the camber based on performance/tire wear, and not touch the body at all. It is easy to keep the tires off the fenders, even though they stick out. The smaller diameter makes it so you drive to the event with a reasonable ride height, then, without messing with the camber curves, CV joint angles, or anything else, you drop it over an inch just by switching tires. The smaller diameter makes the car feel like it has forced induction compared to stock in first gear. 2nd gear ends up in the meat of the power curve, and 3rd is closer to 2nd, meaning potential for using more area under the HP curve. The shifts aren't as frustrating because they often fit in conveniently with the course, instead of being mid straight needing 3rd, then needing 2nd again before the next element. 13" tires, compound for compound, last about the same amount of time before they cycle out compared to 15's, but cost dramatically less. There is more, but bottom line is CSP spyder needs/is best on 13's if you aren't cutting the fenders with a sawzall. Running STR, I will actually miss the gearing change more than all the other race tire benefits.
Interesting, who all makes a 13" wheel that work well on our car? Preferably ones that don't stick out past the fender wells a terrible amount. So the overall diameter of the tire is smaller then?
 

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even though I'll be keeping my car in STR, I have always been tempted to bolt on a set of 13x8's just to have fun at non scca events and shoot for ftd

the gearing and 1" drop sound very tempting
 

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Interesting, who all makes a 13" wheel that work well on our car? Preferably ones that don't stick out past the fender wells a terrible amount. So the overall diameter of the tire is smaller then?
Not all 13" wheels will clear the back bell to the calipers. Most all steel wheels in about a 4.5" backspace with about 1/2" of spacer will work (4" backspace still needs the spacer). Most of the semi-custom or multi=piece alloy wheels will work in a 5" backspace, some needing a few mm of spacer. The 13" wheel is smaller diameter (duh?) and so because the suspension components diverge from the hub area, the smaller back bell diameter requires less backspacing be used than with a larger diameter wheel. This means a 5.25" or so backspace is about the best you can do for tucking the wheels into the fenders on a typical 13" wheel. My advice, if you are setting the car up for CSP, is not to worry about the race only tires sticking out of the fender wells, and to run the largest backspace you can clear (my 8.8 lb panasports in 5" backspace are just about perfect, and might be for sale... :D ). I think the rota RB comes in a +20 offset 13x8 and clears the brakes and suspension on our cars. That would be the cheapest alloy wheel option if you are buying new.
 

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Discussion Starter #18
Not all 13" wheels will clear the back bell to the calipers. Most all steel wheels in about a 4.5" backspace with about 1/2" of spacer will work (4" backspace still needs the spacer). Most of the semi-custom or multi=piece alloy wheels will work in a 5" backspace, some needing a few mm of spacer. The 13" wheel is smaller diameter (duh?) and so because the suspension components diverge from the hub area, the smaller back bell diameter requires less backspacing be used than with a larger diameter wheel. This means a 5.25" or so backspace is about the best you can do for tucking the wheels into the fenders on a typical 13" wheel. My advice, if you are setting the car up for CSP, is not to worry about the race only tires sticking out of the fender wells, and to run the largest backspace you can clear (my 8.8 lb panasports in 5" backspace are just about perfect, and might be for sale... :D ). I think the rota RB comes in a +20 offset 13x8 and clears the brakes and suspension on our cars. That would be the cheapest alloy wheel option if you are buying new.
I was doing some research last night and saw someone on here used V2's, looked like they fit with 225's with no spacers front and rear. I'll probably be picking up a set, they are 660 for a set, which isn't bad IMO.
 

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I was doing some research last night and saw someone on here used V2's, looked like they fit with 225's with no spacers front and rear. I'll probably be picking up a set, they are 660 for a set, which isn't bad IMO.
aren't those 13x7.5? you'll want 13x8.5's for most of the tires, or wider for the 255 hoosier.
 
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