jtswenson

I'm planning to have some forgestar cf5's made in 18x11 front and 18x12 rear for my ZR1. He just needs to know what offsets I need and being new to corvettes have no idea.

Any help would be great. Thanks!

B Stead

C6 ZR1 sizes:

Front wheel, 19 x 10, 40mm
Rear wheel, 20 x 12, 59mm

Front tire, 285/30-19 Pilot Sport Cup 2 ZP, 11.4" section width
Rear tire, 335/25-20 Pilot Sport Cup 2 ZP, 13.5" section width

Proposed setup:

Front wheel, 18 x 11, 40mm +/-
Rear wheel, 18 x 12, 59mm +/-

Front tire, 315/30-18 R7, 12.5" section width
Rear tire, 345/35-18 R7, 13.9" section width

The proposed front setup has 14mm more outside position and 14mm more inside position.

The proposed rear setup has 5mm more outside position and 5mm more inside position.

If there is room to move the setup closer to the outside fenders then moving the front by 5mm and the rear by 7mm would be a reasonable mod. That makes the front wheel offset as 35mm and the rear wheel offset as 52mm. If not then probably just attempt to stay at 40mm front wheel offset and 59mm rear wheel offset.

The last thing to consider are the tire diameters:

Front, 285/30-19, 25.8" diameter
Rear, 335/25-20, 26.6" diameter

Front, 315/30-18, 25.6" diameter
Rear, 345/35-18, 26.8" diameter
.

jtswenson

Thanks! The car is being shipped to me, so I don't even have it yet to check for clearance etc. I was hoping to find someone who's been down this road before and knows exactly what sizes to recommend. Also, I think I'm going to run 345 in the rear if it'll fit.

jtswenson

Also, remember, this is a ZR1, not z06. They're 19 and 20 instead of 18 19. I think widths are the same or similar.

jtswenson

I was planning to run r7s probably. These wheels and tires will be for track only. I'll use the stock set of wheels and tires on street.

Looks like I'll just need to wait to get measurements on the car before I order anything unless anyone can confirm correct offsets for 18x11 and 18x12s.