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Currently too many experts posting different information about the same question.
What is the correct wheel spacer to purchase for a base model C6 corvette with the RPI wide body rear kit?
Main Question:
1) What is the correct spacer size? (1.25) (1.5) (1.75) (2)
2) What is the correct lug pattern? (4.75 to 4.75)? (5x120.4mm)?
3) What supplier sell the best product? (web site)
Parameters:
1) Base model C6 corvette (My car 2005 base model)
2) Base model C6 rear rims 19x10
3) Upgraded to rear panel wide body kit from RPI Design LLC
Goals:
1) Keeping stock rims 19x10
2) Want tires and rims to be nicely flush with edge of wide body kit
3) Do not want to make any mods to lug nut stubs "cutting or sanding"
4) Will purchase lug nuts to screw spacer to rear rotors?
Reason:
1) Later will install 19x12 rims/tire
2) I want to drive car today and not look crazy with small rims
Debate:
1) Is having tires flush with rear panels the correct approach or is having the tires inward or outward with respect to the rear body panel a better look?

Disclaimer: This question is not to debate if I should sell my car and purchase a GS. We all spend our money on what we want to spend our money on. Sometime cost is not our goal.

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ttt

myredhead1

Pretty sure it's 1.5 if using stock base rims. I did the install and am using z06 size rims and tires and will still use a 1/4 inch spacer with extended thread lug nuts as the stock Z rims look hidden underneath the wider stock fender.

Kent1999

When I did this for my 2006 WideBooty, my OEM studs measured 1 5/16" in length. So I trimmed them a tiny bit with a Dremel so they would be flush with the 1.25" spacer adapters I used until my OEM Z06 wheels were ready. There are pockets in the back of most OEM wheels that this tiny bit of stud may fit into, so you *may* not need the lug trim, but me, being the paranoid sort, trimmed them.

The moral of this story is that if you don't want to trim studs, you will probably want 1.5" spacers, but to my eye, the 1.25" spacer looks to be about right when using OEM base coupe rims (see pic below)

Also, 4.75"x4.75"x<thickness> is the adapter size. "120.7mm" is simply the metric conversion of "4.75 inches", so both will fit just fine.

Here is a pic of my old wide-booty 2006 coupe with the OEM Z06 rear fenders, OEM 19x10 rear wheels, OEM size base coupe tires, and 1.25" spacer adapters:

ncvette_1FUNRIDE

1.5" wheel adapters will keep the wheel to edge about the same as your 'narrow' body was originally, if you use the same wheels/tires. If you want flush to the edge you might want to go with 1.75" adapters.

Keep in mind that the GS/Z06/ZR1 rear quarter panels are 1.5" wider (per side) than the OEM regular rear quarter panels.

Also, if you go with 1.5" adapters or wider, you will not have to change or shorten your current wheel studs.


Here was what mine looked like with 1.5" wheel adapters. (I have aftermarket wheels but the same dynamics applied.)



Same wheels on narrow body (no adapter):



Same wheels with wide booty and 1.5" adapters:





Once you get your GS size wheels, just remove the adapters and your good to go.

Sorry, I do not remember where I ordered my adapters from. I just 'Googled' 1.5" billet aluminum wheel adapters for C6 Corvette.

4.75" is the same as 120.65 mm.

You want 5x4.75" to 5x4.75" bolt pattern. Threads are M12 x 1.5.

My wheel adapters were 6061 billet aluminum, hub centric and stud centric.

ncvette_1FUNRIDE

You will NOT rub with 1.5" wheel adapters.

EDIT: That is if you install OEM GS/Z06/ZR1 rear quarter panels.

Some aftermarket wide body fenders that some vendors sell might not work with 1.5". I cannot speak to those.

.

ncvette_1FUNRIDE

I just did a quick GOOGLE and came up with this.

https://www.uswheeladapters.com/prod..._stud-size=141

There are many more website possibilities. I'm sure Summit Racing has them as well.

Kent1999

I wonder if those wheels are the same offset and width as OEM coupe? For having 1/4" more spacer, they look a LOT like my OEMs at 1.25"

ncvette_1FUNRIDE

They are not but it doesn't matter.

Those wheels didn't rub with the regular rear quarters and I added OEM wide body rear quarters (which adds 1.5" width) and the 1.5" wheel adapters and they didn't rub those either.


My question to you is........... did you install OEM Z06/GS rear quarters or aftermarket ones that are fiberglass?

OEM will work with 1.5".

Fiberglass, maybe not.

.

Kent1999

The OP is using OEM wheels. Your width and offset, if different than OEM, certainly could make a fitment difference. If they had more positive offset than OEM, then they *might* be a better fit on 1.5" spacers than the OEM wheels.

ncvette_1FUNRIDE

No it will not. If you use the same wheels/tires that are on a narrow body and you install OEM wide booty, that adds 1.5" width, then install those same wheels/tires using 1.5" wheel adapters, the edge of the tire to the fender will not change.

What happens when you put 1.5" adapters on, it moves the wheels/tires out 1.5".

What happens when you add OEM GS rear quarters, the edge of the rear quarters is 1.5" wider.

Now do you understand?

This dynamic will apply no matter what wheels and offset as long as you are using the same wheels/tires on both narrow and wide body.

ncvette_1FUNRIDE

The only way the edge gap would change with 1.5" adapters is if the rear quarters were something other than 1.5" wider,

I suspect that some aftermarket rear quarters might not actually be 1.5" wider, especially if they are made of fiberglass which is usually thicker than OEM body panels.

I see that the OP bought his panels from RPI. I am not sure if they get OEM panels and paint them or if they manufacture their own fiberglass panels. If they are fiberglass then my experience may not apply to the OP's situation.

If that was the case then the 1.5" adapters may be too much.

Reggied

Thank you my Corvette Brothers
This is very good information, everyone stay on subject

djbrun

I still have a set of base wheels, if you would like I can on a 1.5" spacer on one side and use a plumb to help you make a decision.

With 1.5" spacers they do not look good, they sit in too much.

1.75 to 2" depending on what tires and what looks flush to you.

DJ

Reggied

I think I will be going with 1.75 spacers, Thanks.

Kent1999

Since there are clearly some varied (and unexpectedly passionate) opinions about this topic, I hope you will post back here with some pictures and your satisfaction level when you complete your project.

Reggied

I asked the RPI Designs experts since they are the ones that designed the Widebody kit.

RPI Designs Rep. QUOTE from another post:
Thank you for asking, Here are two different ways approaching it, a scientific way and a non scientific way. First the scientific way, you are installing on Z06 rear 1/4 panels so once installed the rear of your car will be a z06 when it comes to the width of the car, so either you can get new rims that are the 19X12 z06 size and correct tires or you can properly space out your 19X10 with the correct spacers. Here is where the scientific way comes into play. The C6 base Rear Corvette wheel is 19X10 with +79mm offset, the Z06 wheel is 19 X 12 with +59mm offset so the c6 base wheel will have 8 inches of back space and the z06 wheel will have 8 5/16 inch of back space. That means the c6 base wheel sticks out 2 inches from where the wheel bolts on to the hub where as the z06 sticks out 3 11/16 from where the wheel bolts on to the hub. So with this calculation the c6 base wheel will have to come out 1 11/16 or if you want to round it off 1 3/4 of an inch to bring it out where it should be in a safe spot installed on the car. The 1.5 inch would keep the wheel tucked in a little bit and offer better clearance and the 1 3/4 inch spacer would push it out just a hair over where factory it would of been. So if you are looking to use a 2 inch spacer then it would most likely be flush with the 1/4 panel and you might risk the chance it might rub a little bit under a hard load?? Ok, Here is the non scientific way (my favorite one) once you install the wide body 1/4 panels you take you stock c6 wheel and you mock it up, put the wheel in place where you want it to be, hopefully you can see and make sure it will not rub as it goes up and down and you measure from the back of the wheel to the surface of the hub where the wheel mounts to. There you will have the size of the spacer you need. Just make sure with this way you have the car at ride height and the rear suspension is loaded like it would be as you are driving along so you can get an accurate measurement. As far as getting the right look that would be up to the owner of the car, I have seen several different styles of wheel placements on Corvette rear tires where some are flush, some are sticking in a little bit and some are sticking out three inches. That right look really depends on the owner of the car on how you feel the rear tire should be placed


https://www.corvetteforum.com/forums...post1592242110


Thank you RPI Designs for the detailed information..

black.z51.c6

Got mine on ebay, i think they were 100 bucks hub centric 5x4.75 1.5"