I'm looking at buying a set of Boyd Coddington Smoothie IIs, 17 x 8, and was curious what size will fit a stock vette without any complications. I know I need a 5 on 4 3/4, but I'm unsure about the backspacing. The ones I'm looking at are listed as so: 17X8 5-120.65 0P --- Fits Small GM 5 on 4 3/4 Lug Patern, 4.5 inches of back spacing.

Does that sound right?

 

Also, If I wanted to go wsider on the back, what is the biggest I could go with comfortably, assuming I had offset t/a's? What would the backspacing be on thses?

 

the Boyd smoothie II's are really nice lookin rims and i really wanted to get them for my 76 but couldnt because they hit the break calapers so i had to go with the torq thrust II's wich look similar and i am really impressed with them and i dont have any rubbin issues at all. because my rear trailing arms are stock the biggest rims i could run were the 17x8's on both the front and back. i put 245-45-17 up front and 255-50-17's out back and they fit perfect. also here is a link to the website for the company that i ordered my rims from and these guys were a big help when i was trying to figure out what rims to get and it only took two days after ordering from them to get my rims. http://www.newstalgiawheel.com/produ...ils.asp?id=884 hope this helps and good luck.

 

The correct BS for a 8" rim is 4". You also need to make sure the spokes curve outwards to clear the calipers.

 

I just put 18" x 9" BC Smoothie II's on my 79 with 275x18x40 tires (front and back). The offset was 0" which makes the back spacing about 5". No interferences or rubbing. I ordered them through discount tire for $323 each (they are $478 on BC's web site). I had to order the 0" custom offset as the normal offset is I believe 12 mm (12 weeks delivery). I had been running the stock 15" x 8" alloy wheels with 0" offset and 4.5" backspacing and BFG TA radials 25x255x60. The new wheel and tire combination (the 18" Boyds) are about the same overall tire diameter and about 1" wider than the stock 15" wheel/tire combination. By using the 0" offset as on the stock wheels the additional 1" width is distributed equally 1/2" inboard and 1/2" outboard.

 

So, I should be able to use 17 x 8's easily, if you are using 18 x 9's. I just need to custom order a 0mm offset, and my backspacing will be about 4.5". I'm assuming that the 4.5" as opposed to the 4" Zwede suggested will give me a little more room on for the calipers, without sticking out the fender wells?

 

If your sticking with 17x8's youll need 4 inch bs or the tire and rim will look too far in the wheel well,i have boyd starburst 17x8's with a 4 inch bs for my fronts and 17x9.5 with 4 1/8 bs for the rears but i have flares on the rears.

 

Is that with the 12mm offset, or is that with a 0mm offset? I'm pretty sure I want 17x 8s, but all this offset and backspacing stuff gets me confused. Can I go 17 x 9.5 without flares?

 

I have 17 x 9,5 in the rear of mine. I used a rim (+5mm offset)with 5,45" BS and had to add a 1 1/2" adapter.

It protrudes about 1/2" out of each side of the wheel well.

On the inside I have 1/2" clearance

 

Another thing to remember is the more bs you use the closer it is to your e brake bracket,i removed mine ,some guys remount it on top of there trailing arm also.I called tire direct .com for my boyds there a sponsor here on the forum and told them i wanted 4 inch bs for fronts and 4 1/8 for rears and they did it for me.The 17x9.5 like the above ppost will probably stick out a bit past the wheel well,just have to be carefull not to bottom oout and hit the quarter panel,like i did before,thats whay i have flares now.

 

Do they stick out of the wheel wells, front or back? did you relocate your e-brake bracket from the trailing arms, or are you running offsets?

 

Offset is more precise than Backspace.

For 8" wide - negative 1/2" offset.

 

I did not have to move the parking brake bracket. Nor did I have any clearance issues with the calipers. I think the 12 mm offset or the 0mm offset should work with 17x8's. The one thing I'm not sure about with 17" wheels is the clearance to the outboard steering tire rod end. With the 18' wheels it clears easily. One little trick you can do if you have somehow you run into caliper clearance problems is fab some aluminum shims to between the mounting hub of the rotor and the wheel. I think you could go 1/8" or 1/4" and still have enough stud length for saftey. Just a back up plan for anyone who runs into caliper clearance issues.

Offset is the the distance the mounting surface of the wheel is from the center of the wheel. Backspacing is the distance from the mounting surface of the wheel to the outside edge of the flange on the backside of the wheel. The thickness of the flange is typically about 1/2" but can vary somewhat depending on the manufacturer. An example: an 8" wheel with 0 offset would have the mounting surface of the wheel dead center so the distance to each flange is 4". Since the flange thickness is about 1/2" the backspacing would be 4 1/2".

If I had it to do over again I would put 18x10's of 20x10's on the rear with 0 offset. I would have had to move the parking brake bracket and clearance the sway bar a little. I could have run 295 wide tires.

The Smoothie II's have a really unique look. Unlike the TTII's they have a reversed rim and a rolled lip. What is a reverse rim? All wheels have a channel in the rim that the inboard bead of the tire can be pulled into to give the bead room to slip onto the wheel. go look at yours and you will see it. This channel is normally on the outboard part of the wheel. With reversed rims the channel is on the inboard part of the wheel. So when you mount the tire the backside of the wheel is facing up. The rolled lip is just a smooth round transition from the barrel of the rim to the outside of the flange without the little extra edge.

Don't hesitate to ask addtional questions. I spent a year studying this stuff, clearances wheel specs, tires etc. I don't claim to be an expert but I have learned alot.

 

Here is a web site with a diagram that explains offset, backspacing etc.

http://www.rsracing.com/tech-wheel.html

 

Wow - if you've been looking at them that long, you wouldn't happen to have a fairly complete list of 17X8 wheel brands/models that come in appropriate bolt pattern, offset and calipre clearance known to fit C3s would you?

thanks,

 

No, I didn't make a list of various wheels. How comitted are you to 17x8 inch wheels? The reason I ask is after I had ordered my BC 18x9's I found some Centerlines in their bargain basement section that were really interesting. I believe their were 806's. They were nice looking wheels and very light and only $169 per wheel for 17x9.5. Not quite as good looking as the BC smooothie II's in my humble opinion but being lighter weight and a little wider with custom offsets available I thought they were a very good option. If I had it to do over again I may very well have bought those wheels instead of BC's. They are available in different sizes and offsets. There was a picture of a C3 posted on this forum with those wheels installed and they were very attractive. If you wish you can E-mail me and we can discuss this off the forum or maybe we can do it on line so others can benefit. I have mentioned these wheels before but there wasn't a lot of interest at the time.

 

Thanks Megawatt - I'm pretty well settled on 17X8 w/ -12mm offset but I definately like the idea of cheap too. It's not something I'm going to do real soon but eventually. It would be nice to have some selection of decent tires again instead of the 15" mostly junk tires. Anyway 17X8 is pretty much where I've decided I want to be.

Offhand w/o doing any research or having any info avail (am away from my PC) I can recall in 17X8 w/ close offset for C3 a few brands that should bolt on w/o any sort of modification or adapter:

Wheel Vintiques (steel or billet)
Coddington
American Racing
Crager (I think)

Can't recall any others offhand and I don't recall all the model names for each make. Since you did all that work - just thought I'd ask.

thanks again

 

The Centerline 806's are available in 17x8. Here is the web site. http://www.centerlinewheels.com/whee...lt&data=5-4.75

Back up from here and there are other designs in Centerline's "Wheels Deals" section.

Take your time and get what you want and can afford. Custom wheels are becoming a very competitive business.

 

I'm running a 17x9 with 4" BS. 255/50 (27" dia) tire. It fits, but it's close.

 

I have 17x8" fronts with 245/45/17 and 18x9.5 rears with 275/40/18. This is on stock trailimg arms. 4" backspacing up front and 4.875" backspacing in the rear.