Dirty Howie

So I have been checking out a lot of different wheel set ups that many of you have. I have decided on 18x12 rears with 335x30 tires and 18x10 fronts with 295x30 tires. There doesn't seem to be a consensus on what offsets to use. I currently have MMR wheels in 19x12 with 345 rubber that slightly rub on outside of tire and they are a 50 offset. The fronts are not a problem at all with a 30 offset, they are 18x10 inch. I like the MMR and they have a 18x12 but it only comes in the same 50 offset. I'm not sure if I would have the same rubbing with a tire that is 10 mm narrower and wheel that is 1 inch less in diameter........but I am worried about that. MMR does not come in custom offsets.
But the Forgestar F14 does come in custom offsets. So I could get a rear maybe at 55 offset and not have to worry about rubbing. But if I do I would like to figure out what the front offset should be to maintain the original geometry staggered OEM set up. Does anyone ever worry about or consider this or is it only me. Seems like many just worry about largest tire possible. Seems like the aftermarket standard is 50R and 30F like my MMR come in.
Anybody ??????????


DH

Dirty Howie

Okay, since no one replied I will try to simplify my question

I am going to get the following wheel tire combo:
Rear: 18x12 with 335x30 tires
Front: 18x10 with 295x30 tires

Which would you do regarding offsets
1. 50 Rear and 30 Front
2. Custom Offsets : please specify
3. It makes no difference !!!

I am not looking to maximize the cosmetic aspect of filling in the wheel well but rather any performance benefits of picking the best offset.


DH

CaddyRacer

Call Terry Fair @ Vorshlag Motorsports. He set me for my C6Z track rims:
https://www.corvetteforum.com/forums...-on-front.html

Pseudo M

The Forgestar rep that I've been speaking with suggested 18x10 +30 and 18x12 +59, but a 10" wide wheel is a little narrow for a 315 in the front. The order that I just put in is for 18x11 +35 & 18x12 +50 with the plan to run a 315/335 combo.

STANG KILLA SS

#1 dont waste money on a 10" front if your racing the car. get a 11" and run 315s.
depending on how much camber you run your gonna want somwhere around 35-45mm offset.
im running 45mm with 3.4* camber. with that much camber i could have gone less on the offset and still keep them tucked.

street car(minimal camber)= run bigger mm offset. closer to the 45mm. me and my forgestar vendor calculated (each measureing our own cars) up to a 50mm offset would fit to bring the wheel in.
race car (lots of camber) = run smaller mm offset. closer to the 35mm.

with that being said, any time you run less offset, smaller number, push the tire outwards, the larger your tire arc swing will become. = possible front/rear wheel liner rub when turned, and possibly tiny bit heavier steering.

Dirty Howie

59 is the stock rear offset. Not sure why they would recommend that while recommending 30 on the front.
The offsets on the 11/12 combo that you actually ordered sounds like it will stick out about the same as a 10 inch at 30 offest.

Like to see mounted with tires and on the car


DH

Dirty Howie

Thanks for your input.
I don't road race anymore, only AutoX now.
I tried a friends 11 inch front and it feels too heavy, even the 10 inch I notice this but some of it may be due to offset at 30 causing a different geometry than stock. Plus in my 2006 I had to turn all the nannies off or AH was applying brakes on street driving, and I drive 90 miles to AutoX. With the tire sizes I have selected I won't have this problem.
I'm not looking to be the fastest. If I can do better than current 325/275 I will be very competitive.


DH

Craiger77

thats my combo. It fit well




Mine are +50. on the rear 18x12’s. And the fronts are about +40 18x11

Dirty Howie

Interesting. You moved the OEM 12 inch rears outward 9mm but kept the OEM front offset. I think this should have moved your wheel .75 inch outward.
Do you have picture from front of car showing fitment?
How does it handle?
Who recommended this offset to you?


DH

tlrskunk

@Craigar77 As much as I love that Bronze Burst it looks so dark in your pictures I'm worried my CF10's are going to be too dark.

3 more months before I see it in person...

Craiger77

I bought the wheels second hand from another member here who is local to me. The wheels were made to be C6z specific but he had been running them on a c5.
Those were the numbers given to me by him. I can’t say Im 100% sure it’s exactly those numbers, but they fit well. This is the best front pic I have at the moment.
I had just mounted the wheel and the suspension isn’t settled yet in the pic.


Here’s a link to a clip from a trackcross event at Summit Point. The car had so much grip on R888r’s. I know I left a lot of speed/time on the table but I was relearning the limits with the new setup. And honestly rebuilding trust how it would hold.

http://www.getfastevents.com/wp-cont...419pm-fast.htm
I ended up posting 6th fastest for that day in the event.

My alignment specs aren’t overly aggressive. I can post up what I asked for if you want. I just don’t recall off hand.
It’s about:
2* camber in front
1.5* rear.
A slight amount of toe-out in front and a little tow in rear

I followed the pfadt recommendations with a small tweek based on what I wanted afterwards.

Craiger77

They are dark. But when the light catches them it’s not as dark as you see in the pic. I’m always embarrassed by my inability to take a good pic from what I see posted up.

It was very overcast that day, that didn’t help the lighting. They are definitely lighter in person and look good against the blue.

tlrskunk

My car is black and from pics I've seen they look clean on the black.

sccaGT1racer

If you want to be fast you want to put as much tire as possible under the car. The rims that work are 18x11 with a 315 on the front and a 18x13 on the rear with a 345/335 tire. You could get away with a 12 in the rear but there are advantages with the 13. There are many vendors that have the correct offsets. My rears are 56 offset at 13 wide.

Craiger77

The previous owner mounted 345/35/18’s and ran them on track. I would’ve have spec’d a 18x13 rear wheel but these were available now, local, and for a really fair price.

Craiger77

A few pics straight on from the front

Dirty Howie

I called Forgestar and they said rear 13 offset recommendation is 52-54 !! And front 11 at 34


DH

Dirty Howie

First off your wheel look great !!!

The first picture looks like they stick out too far but the pics from above look good. Is there any fender lip contact at full compression??


DH

Craiger77

thank you. No contact that I can see, feel, or hear so far. I definitely think they’re at the limit of how far I want them to stick out.