[cdb95z28]

I think the place to start is to figure out what kind of tire to strut clearance you have with the suspension set at your competition camber, with the OE 1LE wheels and tires. That is your baseline measurement. Find that safe clearance then start playing around on some wheel calculators. This one takes the tire into account, but if you look at this calculator's tire measurement, it is not exact in that measurement. It does not match the tire's section width. For example a RE-71R in the 305 size, the section width is 12.3" while the calculator only shows 12". So take that into account.

https://www.rimsntires.com/specspro.jsp

If at your race camber setup, you know you need (for example) 6mm of tire to strut clearance take that into account as you play with the offsets.

This example would be the 1LE front compared to a 305/30-19 with an offset of 10mm. This gets you close, nothing can be set in stone until you actually try a wheel/tire on the car. So keep in mind that you are only within a few mm's of what you need.



I do not think there are many 19x11" wheels out there (short of custom) in an ET10mm, so for example I've seen an ET25, so you'd need about a 15mm spacer, and longer studs to make the spacer work. I'm looking at wheels with an offset that I know is close and it can be fine tuned by adding a spacer.

Of course by duplicating the inner tire to strut clearance, this pushes the additional width out past the fender edge, which if it is to much, would look funny.

[Summit1le1ss]

I have to ask though what is the motivation to go to a square setup?[/QUOTE]

Rotate.
She's my DD. I'm coming from a 15 GTPP and ate rear tires Evey 5-8k. After squaring the set up with two back rims was able to extend tire life greatly, more than double. You'd think I'd just be replacing all four around 10-16k, but it was more like 20k. It's just a though.

[glamcem]

I will be running 305s all around also but not on 19X11 front wheels.. The offset of the OEM rear wheels would probably an issue since the fronts are +20mm and more importantly 10"

I will report back if I ever run into rubbing issues with 19x10.5 +22mm wheels

[RUQWIKR]

I tried it early on and hard interference to strut with the rear wheel on the front. Wasn't even close and would not sit flush on the rotor hat. I did not do the stack up for how much of a spacer it would take to clear to not modify a spring perch. In fact, if you get yours on the lift, the front wheel is very close to the strut. If you look at the spring perch on the upcoming ZL1 1LE, there is way more clearance, and is why the 11" fits. They have 0.5" wider fenders and a narrower perch.

[cdb95z28]

Originally Posted by RUQWIKR

I tried it early on and hard interference to strut with the rear wheel on the front. Wasn't even close and would not sit flush on the rotor hat. I did not do the stack up for how much of a spacer it would take to clear to not modify a spring perch. In fact, if you get yours on the lift, the front wheel is very close to the strut. If you look at the spring perch on the upcoming ZL1 1LE, there is way more clearance, and is why the 11" fits. They have 0.5" wider fenders and a narrower perch.

The 2nd picture is with the OE 11" wheel? How about a 19x11" wheel? That may solve the diameter clearance.

[1LE caSSper]

I agree on all flats I swear by square track setups I ran staggered on my m3 vs square 285 on my '14 boss 302

Aside from off track advantages rotating tires saving $ Tire life etc the natural balance is 10 fold easier to find and feels better mid corner on off throttle transition.

We'll hopefully find a safe solution for square soon

[glamcem]

Originally Posted by cdb95z28

The 2nd picture is with the OE 11" wheel? How about a 19x11" wheel? That may solve the diameter clearance.

I believe so, I would highly doubt that it's the factory 20x10 fitment
Rear wheels also have +43 offset compared to +20mm front offset so that would also explain why it sits so close to the suspension.

I should receive my wheels sometime this week (and the car early next week lol). I will be running 19x10.5" (+22mm offset) front wheels with 305/30/19 Trofeo Rs, I will post some pictures for those who might be interested

[V1LE8R]

Here's a test fit of an OEM Z28 front wheel. Granted, no tire, but the wheel itself clears. Barely. 11 inch width. Going to try a 305







Sent from my SAMSUNG-SM-G935A using Tapatalk

[tx6g1le]

Whoah that's close! Look forward to seeing what the results are.

[booyaa56]

Negative camber plays a role in this conversation. Just had my alignment done with -2.2 camber up front , went with my 19X10 24mm offset and 305 Bridgestone square setup and no issues

[Summit1le1ss]

Looks good. Can't wait to see if tire fits. A few small spacer will do wonders if close, say 5mm.

[glamcem]

Originally Posted by booyaa56

Negative camber plays a role in this conversation. Just had my alignment done with -2.2 camber up front , went with my 19X10 24mm offset and 305 Bridgestone square setup and no issues

I would think the opposite; adding more camber should put the upper side of the wheel closer to the struts as you give more angle.

Just curious; Were they able to get -2.2 camber with completely OEM strut and plates? Any camber bolts?

[glamcem]

Originally Posted by V1LE8R

Here's a test fit of an OEM Z28 front wheel. Granted, no tire, but the wheel itself clears. Barely. 11 inch width. Going to try a 305







Sent from my SAMSUNG-SM-G935A using Tapatalk

That's a tight fitment for sure considering that it's only 3mm closer to the struts vs the OEM setup.
Is this street alignment?

If so I believe I will definitely need to get some sort of extended studs so that I can fit a 7-8mm spacer safely. Without changing the OEM studs I wouldn't use anything wider than 5mm :/

[AZ_1LE]

Originally Posted by glamcem

I would think the opposite; adding more camber should put the upper side of the wheel closer to the struts as you give more angle.

Just curious; Were they able to get -2.2 camber with completely OEM strut and plates? Any camber bolts?

With a McPherson strut-style suspension, camber in this case is changed by pulling the top of the strut in towards the middle of the car. The wheel and strut move together, so there is no increasing or decreasing change in distance between the two.

The only other way to change camber would be to change the dimensions of the lower control arm(s), or ball joint(s).