Wheel offset for 456GT vs. 550/575

Yep. A few 456 F-Chaters have and here's a '95 with the stock 18" 575 wheels. Personally I think it looks great.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=6212&item=4539022648&rd=1

 

I think Auraptor started a thread with the various model wheel offsets listed.
Whilke the 550/575 wheels do fit, I don't believe the OEM offsets are the same.

 

Hey Stephen...You be right....The offsets are different. However, the 575 wheels fill out the fender well at bit more and we all like that!

 

The offsets are different and that was my car on Ebay.

The 550/575 fronts are +7mm vs the stock 456 wheel
The 550/575 rears are -2mm vs the stock 456 wheel

The front offset for the 456 is 50mm (8.5"wheel) and the rear is 24.6mm (10" wheel) this is based on the 17" wheels

The front offset for the 550/575 is 43mm (8.5"wheel) and the rear is 32mm (10.5" wheel) this is based on the 18" wheels

550 front 255/40/YR18 and rear 295/35/YR18
456 front 255/45/YR17 and rear 285/40/YR17

No issues with either, they plug and play. FWIW, I like the extra width on fronts, but added 15mm spacers to the rear to gain some width.

Below is a cool utility which tell you all you need to know. The biggest issue is to mkae sure the wheel clears the calipers and the control arms on the suspension if you deviate from the stock set up.

http://toy4two.home.mindspring.com/offset.html

 

http://ferrarichat.com/forum/showthread.php?t=8361&highlight=550+wheel+offset
Original offset thread. 550 front is 46mm not 43mm.

 

It is a typo, it's actually -7.4mm, or put another way, you need to install a 7.4mm spacer to have it sit like your standard 456 wheel.

 

Stephens, Your offset calculation (7.4mm) is based on a 10.0 " wheel, my calculation is based on the 10.5" wheel of the 575. The rear sits inward -2mm compared to the 456 wheel.

Current Wheel Width 10.0 inches Current Wheel Offset 24.6mm
New Wheel Width 10.5 inches New Wheel Offset 32 mm

Your new wheel will have the following chracteristics:
The clearance from stut housing to the inside of the wheel will be 14mm LESS
The outside edge of the wheel will RETRACT in towards the body by 2mm

Christian

 

Christian is your car still for sale?

 

Since your old and new wheel widths are the same, the arithmetic is very straightforward:

Front
(+52mm offset on your new 19" wheels) - (+50mm offset on the stock 456 wheel) = 2mm spacer required (or probably close enough to ignore)

Rear
(+58mm offset on your new 19" wheels) - (+24.6mm offset on the stock 456 wheel) = 33.4mm adapter required (or say a 35mm adapter if you can tolerate moving the tire outboard another 1.6mm). 33.4mm is too large a distance for the spacer approach IMO (and an adpater doesn't require longer lugbolts)

 

No. The spacer makes up for the difference in the wheel construction ("offset") only -- i.e., if you used the same size tires, the outboard and inboard tire sidewalls would be in the exact same locations as the stock situation. If you use those calculated thickness spacers and go to a 295 tire versus a 285 tire, the outboard tire sidewall would be 5mm further out and the inboard tire sidewall would be 5mm further in (but you've got the right concept -- those calculated spacer values put the new wheel centerlines in the exact stock positions. If you want to fudge a little in or out, just change the spacer thickness by the amount/direction of the fudge that you desire.)

Some manufacturers do offer bolt-thru spacers (using longer lug bolts) that are up to 40mm thick, but at 25mm or more thickness I think it's better to use what I would call an "adapter" where the adapter gets bolted to the hub using a set of bolts that you don't see once the wheel is mounted and then the new wheel gets bolted to the adapter (using the stock lugbolts for the new wheels). Hill Engineering calls these "Type 2 Fixing" spacers -- see:

http://www.customferrariparts.com/homemainferrari.htm

and click on "wheel spacers" on the left:
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