17" 6 pin wheel specs?

SSSammy · #1 (**permalink**) 10-03-2010, 05:43 PM

Thinking about getting a set of 17 inchers so I can have more choices for tracks that have a street class (like Run N Gun). I see PSE and Vintage offer the 17" Halibrand replicas in custom backspacing and offsets. How do I spec these wheels for my ERA 427 SC with 6 pin option? I read the info on the ERA 427man site about what the backspacing should be for each tire size and rim width. Surely the offsets are different for a 17" wheel 9" front rim and a 11" rear rim than they are for a 15" wheel width 7.5" and 9.5"???

thanks!
Sam

undy · #2 (**permalink**) 10-04-2010, 03:33 AM

Don't know about ERA, but the SPFs run 4 1/2" back spacing in the front and 4 3/4" back spacing in the rear using Vintage's 17" 5 pin offerings. My LSC uses 5 1/4" front and 5 1/2" rear backspacing with Vintage's 5 pin, 17" knock offs. They're all using back spacing as their point of reference, not offset. I'm pretty sure if you talk to Bob @ Vintage he'll know off the top what backspacing's needed for the ERAs.

strictlypersonl · #3 (**permalink**) 10-04-2010, 04:02 AM

For some reason, I didn't have all the front specs. Fixed.

Wheel Offsets

Clois Harlan · #4 (**permalink**) 10-04-2010, 07:43 AM

Sammy give Bob a call he has done all the math for the different makes of Cobra's. I think he will give you a Run N Gun discount.

Clois

SSSammy · #5 (**permalink**) 10-04-2010, 07:56 AM

Quote:

Originally Posted by strictlypersonl

For some reason, I didn't have all the front specs. Fixed.

Wheel Offsets

Bob, I am missing something ...

Per the chart you refer to:

Front Wheel 9.0"W x 17" gets 4.75" backspace. What is the offset? .8" like the 7.5"W x 15"?

Rear Wheel 11.0"W x 17" gets 4.3" backspace. What is the offset? 1.7" like the 9.5"W x 15"?

Just want to get it right before I make the call in case the supplier needs me to say what it should be for an ERA.

Thanks very much,
Sam

RICK LAKE · #6 (**permalink**) 10-04-2010, 09:40 AM

Sam ERA had to modify my cobra for 17" wheels. The body as been trimmed and fillers to clear. The other thing is to talk to Bob about the P/S setup. He didn't have the numbers of the rack in my car. I do have the specs. 2.0 ratio. 17" length. The other problem is there are only a couple of 17" tires with low wear numbers over 200. Pilots are 220 and cost through the eye sockets. I will see if I can find a # of the appleton rack for you. Rick L.

strictlypersonl · #7 (**permalink**) 10-04-2010, 10:38 AM

I pretty much gave up giving wheel makers the actual offsets (which is the most accurate way to define the wheel). Most of them only want the backspacing. You can figure the offset by adding about .8" (an average edge width x 2) to the nominal width, then dividing by 2. The difference between that number and the backspacing is the offset.

Just to make things even more interesting, not all companies define offset in the same direction, so it's best to send them a well-defined drawing.

SSSammy · #8 (**permalink**) 10-04-2010, 10:57 AM

Quote:

Originally Posted by RICK LAKE

Sam ERA had to modify my cobra for 17" wheels. The body as been trimmed and fillers to clear. The other thing is to talk to Bob about the P/S setup. He didn't have the numbers of the rack in my car. I do have the specs. 2.0 ratio. 17" length. The other problem is there are only a couple of 17" tires with low wear numbers over 200. Pilots are 220 and cost through the eye sockets. I will see if I can find a # of the appleton rack for you. Rick L.

Dunno, Rick .. my chassis is a "Gen II" post ser # 731, which had numerous changes from the earlier version. The 26.5x10 Billboards fit, with an occasional rub. They are about 12.5" section width in back. The 26.5x8.0 are about 11" wide in front. I'm using that as a "do not exceed" template.

I'd appreciate the info on the power steering rack!

Sam

SSSammy · #9 (**permalink**) 10-04-2010, 02:17 PM

Quote:

Originally Posted by strictlypersonl

I pretty much gave up giving wheel makers the actual offsets (which is the most accurate way to define the wheel). Most of them only want the backspacing. You can figure the offset by adding about .8" (an average edge width x 2) to the nominal width, then dividing by 2. The difference between that number and the backspacing is the offset.

Just to make things even more interesting, not all companies define offset in the same direction, so it's best to send them a well-defined drawing.

Thanks, Bob. I can work with that. Just want to know all that I can know about it.

Sam

RICK LAKE · #10 (**permalink**) 10-04-2010, 02:31 PM

Sam We could have taken my wheels off and try them on your car. Then you would have had an idea about fit. Mine are 335/ 17" The other thing is to increase the spring rates on the car to stop body roll and leen. I will call you in the evening. Rick