tstiles

Am I missing something ? .... Everybody seems to be running 17 / 18 " combo or 18"s all around.

For a DE instructor on a budget , why not just run 17" wheel / tires all around and save $ 300 per set of tires ?

Is there a significant performance advantage / disadvantage ?

I may run some NASA TTA in this car .... What are the thoughts there ?

Thanks ,

Trey

KBRVETTE93

17" all around is good.

Scuffed 18" race tires are available for less money, for those on a budget.

6SPEEDZ

i run 17's all around on my Z06. my buddy ran the car that way also in TTA and has set records that way. i think it depends on the track and tire compound as far as how big of an advantage the 17 18 or 18 18combo will give you.

Independent1

17's all the way around is good. Might find the following article of interest.

http://www.vetteweb.com/tech/0301vet...ims/index.html

tstiles

OK , Sounds like 17's all around are a viable option.

So , What changes on the set up with the following assumptions :
- NASA TTA
- Toyo RA1
- Stock C5 Z06

Tire Sizes ?
Camber / Caster / Toe ?
Shocks ( Thinking 04 Z06 ) ?
Ride Height ?

I've spent 20 yrs in low HP cars ( SR / SRF / F2000 / SM / S2000 ) , so I'm guessing my overall style will not change much. Smooth / Controlled trail braking / early on the throttle.

What have I missed ?

Thanks in Advance

Trey

Independent1

^^Different cars demand different driving styles. The corvette is a high horsepower car. I am guessing that you will probably be taking more late apex corners so you can put the power down sooner. With low HP cars you need to carry as much speed as you can through the corners since it is so hard to make up for any loss of speed.

You will want the car as low as you can get it without adversely affecting the handling to lower CG and improve aerodynamics.

John Shiels

17's are OK but 18's are better handling.

Jason

I mostly run 4 17's, but I have 4 18's in case I find tires priced right.

L98Terror

2007 TTA National Champion ran 275 40 17s all around, so it can't suck

Jim 47

17's all around work just fine. I have 275x40's in front and 315x35's in the rear. The 17's keep the car lower than the 18's and there is good balance between the front and rear. Also the choice of wheels and tires is much better with the 17's.

Jim

johns68

17x11 with 315/35 all around. Car is very balanced, and the V710s last significantly longer with front/back rotation. They stick out a touch in the front, and rub the DRM brake ducts at full lock, but I'm very happy with them ...

http://gotbluemilk.com/web080926/23/...es/image7.html

Git Er Dun

I had 17's with 275 front and 315 rears but switched to 335/30/ZR18's on all 4 corners. I was looking at going with 335/35/17's but 17's would not have been able to run front offsets around on the whole car because with the 18s I can use a front offset and rotate them around the car with a 1/2" spacer in the rear. Also when I am going to put a 6 piston front caliper and bigger rotors on they will clear the 18's but not the 17's. BTW I run 18X12 CCW Classics.

John Shiels

When I run my 17's they are a tad slower but much harder to drive than 18" What is TTA class? What mods are allowed?

wallyman424

I hear that guy's a hack though.

John Shiels

I don't think tire choice is a problem now as it was few years ago when most cars were 17's. Diameter is in the fractions of an inch in most cases then divde that by 2 and it is not much. 18 are better under braking with ore rubber IMHO.

6SPEEDZ

The only thing 18's do for the same size as a 17 in width is give the car more spring rate. the down side of 18's over 17's in general is more rotational mass. so a 18 takes more to accelerate and slow down than an 18.

L98Terror

C66 Racing

17s shouldn't have any impact on ride height. When going from a 17 to 18 or visa versa, the overall tire diameter should be kept about the same to ensure ABS and the TC/AH systems work. I've read that keeping the overall diameter within about 3% of stock will result in satisfactory performance of these systems.

The stock C5 Z06 fronts are 25.4" in dia, the rears 26.1" in dia.

In SCCA T1, we are limited to 17" wheels by rules. We run 17x10 front, 17x11 rear and guys usually run either 275/40-17 front, 315/35-17 rear, or 315/35-17 all around. The 275/40-17 are 25.5" in dia and the 315/35-17 are 25.6" in dia. Both within 3% of the stock sizes.

Given my own choice, I'd probably use 18 front and 17 rear. The 18 front would have a lower sidewall and improve turn-in response. The 17 rear a bigger sidewall to give more flexibility and help put the power down. The 18 fronts would also allow the option of bigger front rotor (again which I can't do in SCCA T1).

The tires themselves weigh about the same. For example, according to Tirerack, the Hoosier A6 315/35-17 (dia 25.6") weighs 27lbs, and the 315/30-18 (dia 25.6") also weighs 27 lbs. But the 18" wheel will in general weigh more than the 17" wheel.