Bmwmike

Thank you. Yes the rear i was referring to. Im going for a 325/30/19. Im hoping it works out

savage

Please let us know how the 325 19's work out for you( if I was trying that I would go with a 83mm offset , but that's me) good luck keep us posted!

X25

Someone posted in another thread that these O.Z. wheels work:
Front, O.Z. Superleggera 19x10.5 59mm, 295/30-19?
Rear, O.Z. Superleggera 19x11 75mm, 315/30-19?

I'm not necessarily interested in these wheels, but if these dimensions work, it could be a winner. I think one could even use 305/30/19 tires on all corners (the rears would be a stretched a little more like what Camaro SS 1LE and Z/28 does) with this setup. Thoughts? Any wheel manufacturers that produce wheels similar to these offsets and sizes?

Part of the problem I see is that people still don't know or share what offsets are optimum for this car. I know exactly what offsets would work for my Camaro SS 1LE, but I have no idea what the range is for a C7 Z51 besides a few examples that worked. Since I intend to upgrade the brakes with 15" StopTech kit, I'm shunning away from 18" wheels, just in case they don't fit.

Bill Dearborn

As I posted before I have a C7 Z06/Z07. My 18x11 front wheels fit over those big brakes. Just barely but they do fit. The only issue you may have is offset because the base car may be different than the Z06. CCW has been fitting wheels to the C7 since it came out and they know what will work with which brakes you are looking to upgrade to. The main issue with CCW wheels is the large diameter of the part of the wheel that fits against the rotor. It is larger in diameter than the depressed areas of some rotor hats. Not by much but by just enough to cause a problem.

If you go with a rotor hat that has a flat surface you will not have to worry about mounting a spacer to fill a depressed circle in the middle of the hat.

Bill

X25

Oversimplifying wheel shape/design differences and their impact:

C7 Z51 OEM wheel specs:
Front: 19-inch x 8.5-inch 56mm offset (with Z51) - Rear: 20-inch x 10-inch 79mm offset (with Z51)


C5 Z06 rear wheels are known to barely fit up front, and they're:
18"x10.5" ET58

Therefore, C5 Z06 wheels are 27mm closer to the suspension, yet they barely clear. As such, we can say that we should not get closer than 25mm inwards with new wheels up front.

18"x10" wheel with stock ET56 offset would be 19mm closer, but would also stick out 19mm more.

My theoretical optimal front wheel for Z51 at 18": 18"x10" wheel with ET62 would be 25mm closer inwards, but would only stick out 13mm.

This is the wheel config I'm thinking about. I asked CCW what offsets they would recommend, but they were secretive about it until I put the order. I don't know the point in doing so since we share our wheel specs in the community already, but anyhow, I will get to the bottom of this soon.

If we have a similar buffer zone inside of the rear wheels at 19", one would think 19x11 would be an easy fit, since the buffer is already within the size bump to 19x11. I would also like to increase the rear track width similar to the front increase I proposed (fronts would increase 13mm on both sides; about an inch overall), so I would reach at:
19x11 ET79 (stock offset) would get closer to suspension, and stick out by about 12mm (perfectly comparable to fronts I proposed) I would push it 2mm towards interior, making it 19x11 ET81, which would be 14mm closer inside, and 10mm more sticking out.

Update:
-----------------------------
More examples:
Wheel Model: Vertini RF1.2
Wheel Sizes: 19x9.5 Front & 20x11 Rear
Offset: 50mm Front & 73mm Rear
Construction: Rotary Forged
Bolt Pattern: 5x120.65
Center Bore: 70.3

HRE FF01 C7 Stingray wheels are offered in the following fitments:
Front 19x9.5 55mm ET
Rear 20x11 73mm ET

--> There seems to be a consensus of 73mm for rear offsets on 11" width.
If Vertini wheels don't stick out at 19x9.5 at 50mm front, it means I could do the same at 10" wide with 56mm offset. I already know there is enough space inside.
-----------------------------

Conclusion:
My imaginary ideal setup would be
18x10 ET56
19x11 ET73

Perhaps this topic merits a separate discussion thread. I am very surprised that Corvette forum community does not know exactly what range fits, and what doesn't (even though exact is too strong of a word). Miata guys know, Camaro guys know, EvoX guys know, S2000 guys know, FT86 guys know... why not Corvette guys : )

savage

You not talking/ thinking about tire sizes to on these offsets!
Ok, for me to run 315's up front on 18x10's my 60mm offset wheels require less camber than 58 mm ccw's , 3.1 neg camber. I really don't think I could get enough neg camber to run the 56 mm offset your thinking( 295's or smaller but not with 315's) in the rear I like the 18x11 ( the 19x11 takes a inch of travel from you) I have my 18x11's offset 78mm ccw's and 79 offset forgeline with 335/30/18's on them( I need that extra inch of travel so the tire doesn't hit the rear inner lip) my tires in the rear stick out; the 335 will never fit inside wheel well , I really don't think a 325 Hoosier will fit in wheel well eather so going with the 19 inch wheel and 73 offset that tire might smash the inner fender lip. That inch of travel I feel makes the difference , also I'm doing this with a z51 mag-ride car in track mode( stiff mode) I really don't even like a 315 on your rear wheel with the 73 offset( I would go 79 - 83 ) I hope this helps, I have more time and money that I want to think about finding out what will work on our skinny cars.

Chets LS3

X25 I inderstand ccw can make anything you want. But based on what you want, you could look into this;

Cray spiders; 18x9.5 56mm. 19x11 76 mm offset.

I personally have this setup with some decent camber on the car and running a 27.2 inch tall Pirelli. The tires tuck in the rear just find and the fronts clear. Atleast on a Pirelli 275/305 combo.

X25

Thanks for the great feedback. I actually placed the order for my wheels at 18x10.5 ET57 and 19x11.5 ET83. The tires I got are also about 0.5" shorter than stock tires of front and rear, so I hopefully that will help, too. They are 275/35/18 and 305/30/19.

I don't know enough about this car's tire needs, yet, but I wonder if we really need anything bigger than 305s on it. 305-325 width range is considered ideal for Camaros, and we are talking about a 2-ton car here. This makes me wonder if we'd ever need more than 305s for a 3350 lbs car (base 1LT Z51). I suppose this merits its own discussion.
That sounds like a great choice!!! Your tires are too tall, though. Why not pick something with less diameter?

X25

By the way, can we get those aggresive cambers without having to modify the suspension? I suppose I need to pull all the washers out of the upper cnotrol arm mounts?

Chets LS3

Removing washers can get you more negative camber. I have a 27.2 tire due to running a takeoff 305 Pirelli slick. Computer acts fine and it works. I can run a 295 that's a 26.8/9 inch tall tire.

Jet Vet

A lot of great info and discussion here since my original post. Here is what I finally decided on, and I placed my order with CCW today.

'Corsair' model C140 wheels,
18x10 (64) up front with R888 275/35-18
18x11 (76) in back, with R888 305/35-18

Those combinations have diameters which are nearly identical to the OEM 19/20 wheels with MPSS tires.

JV

Magister Ludi

Thanks for the update. Let us know how they fit.

savage

If you want neg camber you need to pull washers( it makes it so easy then) All removed from front, half from rear<br ><br > <br > <br >

X25

Great, thanks!

savage

One more thing, I see some of the posts guys talking about running 275's up front and 305's in the rear. What I did to run those sizes ( ss in scca, next year AS) is just pinch those tire sizes on factory base wheels!! I have a z51 car and when I run SS in a scca event I run base wheels( yes they fit perfect) with 275's up front and for now I run 285's in rear waiting for the r71r to be released in a 305/ 19. Base wheels even the double spoke 2016 ones are cheap! Bobs housed wheels sells 14-15 and the 2016's for about 1 thousand delivered . Just saying, yes those tire sizes would work better on wider than stock wheels( then your not SS your SSP)just wanted to give as much information as I got, thanks for reading

X25

I used to use stock wheels with much larger tires, too, as long as they were deemed safe. The obvious problem is that the contact patch is not actually much wider than what the stock tire would provide, since the tires are pretty much compressed from the sides by the wheel. What's more, the profiles of the tires also bubble up, messing with your suspension (since it becomes more of a suspension part, interfering with your dampers). In Miata world, you always stretch the tire as much as you can for best performance, and the impact is proven by all the autocross times in the forums. In the Camaro world, GM has also realized the impact of this when they shod ZL1's 20x11 rears with 285s, which worked great for 1LE. In fact, when they came up with Z/28, they still went with wider rear wheels, even though all 4 corners were shod with the identical tire at 305/30/19.

In short, I know there are very good economical reasons to use the stock wheels, but we should also note that the performance will be significantly impacted. I'm sure you know about this already, but we might be having different opinions on the magnitude of the 'impact' : )

savage

I agree, why I needed to pinch wide tires on skinny wheels is to stay in stock class( no wheels width change to stay in stock class) and let's not forget the much better heat sink a larger tires gives at the track, and as I said I agree with what you said but I do have a BUT!! Here is a fact I can't explain, the best corvette drivers/ cars in the SCCA running SSR all run a 315/30/18 Hoosier on the factory 18x9.5 wheel ( that is a pinch and a half) I can't go to a event and not see every c6 zo6 not running 315's up front on the 9,5 wide wheel. My childhood friend that has a 2007 zo6 from new who only ran 285's up front I talked into buying the 315's last year for his big event Giant despair hill climb in Wilkes barre, pa , he took 1 1/2 seconds off his best time ever last year. ???, as much as I was told it won't work , all I see is success doing it. I wish I really knew!

X25

T1 is designed for FE3 springs, which are found on Z51 with no magna ride. If you buy the kit on any other model (like base Stingray), I'd recommend getting the springs, too.

LT5Vette

Question for X25. Researching the tire wheel choices, have a source for hoosier take offs but looking for sizes that fit and work.
Have you gotten your wheels and tried them out yet?
Thanks

X25

Yes, I've been running with my wheels for about a month now, and had 4 track days so far; they work well.

CCW changed the front wheel specs in the last minute to accommodate StopTech BBKs (which I ended up canceling):
18x10.5 ET52 (used to be 57) and 19x11.5 ET83

If I were to order them again, I'd push wheels a tiny bit outside on both front and rear, something like 18x10.5 ET51 and 19x11.5 ET80. This way, I (almost) could prevent upper control arm touching the wheel when the car is on lift (it doesn't happen when it's not on the lift or jacks).

Anyway, I've been running 275/35/18 and 305/30/19 NT01 tires with no rubbing issues at stock Z51 height. Once I go through all my tires (I have a new spare set), I will try 295/30/18, 325/30/19 Trofeo Rs to see if wider tires help with the dynamics of the car. Coincidentally, those sizes are also available from Hoosier.

I would like to note the obvious here that the wheel width, i.e. having wide wheels is crucial to proper handling. Stuffing much wider tires on the same (stock) wheel or relatively narrow wheel will not provide similar results. The biggest factor in improving contact patch is the width of wheel (and only then comes the tire size).