yours is the one I'm trying to replicate in stance. I already have a VBP 360lb spring and 8" bolts at the max lowering, I removed my 9" bolts but might have to go back with the slightly lower profile tires. Are you running the stock rear sway bar? I'm relocating the Ebrake just bc I already had to zip tie the cable out of the way to clear the 255s. I would need to pick up another set of .5" spacers to achieve the 4.75" back spacing in the rear. I use an online diagram calculator and my 18x8 with 4.5" backspacing is slightly less than your 18x9.5 with 4.75 back spacing. About a 6mm difference that yours pokes in further than mine. You had no clearance issues with that? I've heard 4.5" on the front is a bit much. I might have to pick up some 3/4"-1" spacers to push the wheel out but yours stick out 32mm or 1.29" more than mine would with the 4.5" backspace.

 

Not the factory rear sway bar, VBP product. Her are the clearance picture with my VBP 360 rear suspension kit. I used the factory sway bar links on the TA and added a heim joint to connect to the sway bar.

 

Gotcha, I wonder if the stock rear sway bar will be an issue then. I def don't want to mess with the new to me VBP spring. But yours looks close and thats .5" further out than my 5.25 BS.

You sold me on the wheels, I'm going 18x9.5 all 4. I canceled the 245 tires and I'm going with 275/40 all the way around. The 5.25 backspacing will have to drop to below 5.1" to clear from the 80's guys in this thread (wider flares). To get to your 4.85-4.75" BS I can use 15mm bolt on spacers on the front if needed and do maybe some 1/4" slipons on the back if needed. I'm getting a great deal on the tires at $150 for 2022s Bridgestone Potenza sports so they are only #30 more than the 245 tires I ordered. I will be placing the order for the rims soon.

 

New meats arrived yesterday and relocated pass side parking brake bracket. It was terrible trying to get the cable out the back of the caliper without removing the caliper. The caliper back bolt is shrouded by the stock rear sway bar and brake line.


Relocated pass side parking brake bracket. What a PITA!

Old 255s vs new 275s

 

need some help guys. So 3 of the 4 rims arrived today and I attempted a test fit. These are 18x9.5 with 5.25” backspacing or zero offset. I used a centric ring that I sanded down to fit the 70.6mm hub on the rear wheel. I bolted the rim up and man this thing is super close to the trailing arm. The rear spring bolt Washer is basically touching the rim as well. The rear spring is a normal length VBP and I’m using a 8” bolt with poly bushings. This is with the car in the air and suspension unloaded, when I pull up on the wheel the spring bolt/washer pulls away alittle. I have a few thin spacers 5mm and 3mm so I tested a 5mm which made me feel better with the rim to trailing arm distance and a bit more from the washer. But then it pushes the centric ring out more which I don’t love. Anyone else have this issue or it’s this close with a 9.5” wheel and 5.25” backspacing? Am I freaking out over nothing?



No spacer rim to trailing arm

No spacer rim to sway bar

No spacer wheel to spring bolt washer

With 5mm spacer wheel to trailing arm

With 5mm spacer wheel to spring bolt Washer

 

1/2" rim to trailing arm? That's fine, wheels do not flex. I ran much less, and had zero touches, on my Pro-Solo car, 1/8" rim to a-arm.

Spring bolt washer - hmmm - that part moves around. It really only matters at ride height, and maybe 2 to 2-1/2" lower. (Trailing arm is dead level at ride height.) If it is OK there, I would call it good. Full droop is only on jackstands and is irrelevant, u-joints bind there anyway. But many guys run a rear spring shortened 1/2" on each side for just that reason.

Tire sidewall is usually the real limiting factor. The biggest bulge is about 2" larger than the rim lip. And Depending on tire size can be wider than the rim. It tends to touch the upper frame, and rear swaybar first, and trailing arm 2nd. The tire tread corner tends to touch the rear frame by the shim pocket, about 4" higher, you can see where the metal is fatter and reinforced by the edge of the pocket. Even if it clears everywhere else, if you tuck them in tight, it may still rub the frame paint by the spring pocket once in a while. I'm OK with that, but some aren't. Often the rear swaybar gets re-bent or removed.

Yeah it gets that tight with that rim size. You'll have to get the backspace and/or spacer just right.


What tire size are you planning?

A 275-40-18 is kind of C3 common, and that rim should be 10.5" wide on the outside of the rim, and the tire sidewall should be just a little wider, say 10.9" on that rim width. That sidewall at the pocket or the swaybar is likely your limit. I would keep that 1/4" away from hard parts because the sidewall will flex.

 

thanks, it feels tight but 1/2” seems like a lot according to you. I moved the wheel to each spot and did some
measuring. It’s about the same on the other side (rear) about 1/2” trailing arm but only 3/4” from the sway bar. Both fronts fit great, I have about 1/4” gap from the edge of the tie rod and that’s the tightest spot but it’s inside the wheel DIA.

the ET lugs are perfect and give me full engagement on the stock studs and they center the wheel perfectly. I counted a solid 14 full threads with the ET lugs and with the stock wheels/lugs I counted 10. I read 8-9 full threads is the minimum. I would really love to not run any spacers. With the hub centric rings and the ET lugs it’s perfect. I guess I wont know for sure till I get the tires mounted and wheels with the car on Dollie’s to check it all out.

yea, tire is 275/40r18. They shouldn’t bulge much past the wheel edge. I run the same size on my other car 18.9.5 and it’s almost straight up and flush with the wheel edge.

 

Yeah sounds tight but still clears.
I would cut out a piece of cardboard just like that outline you have, to simulate the tire sidewall, and tape it to your wheel.
Check sidewall clearance at rear T/A pocket, T/A arm, sway bar etc.
Once you mount a tire to the wheel they can't be returned. But tape cleans off easily!

I'm glad the front clears the tie-rod. That's close but OK. On the front tire, the sidewall or tread corner may touch the frame by the steering box bolts, and the front lower f/g fender lip, but only at full lock. Depending on tire size some guys trim the front bottom fender lip 1/4" for about 4 inches. The factory did this on 75 or 78+ when they went to the 255/60s. My front tires on my solo car would always polish the paint off the frame with the tire, but there is little reason to turn the wheel to full lock anyway, so just don't. A little rub once in a while means you are not wasting any space! It never hurt my tires, cause it was only while parking, at really low speeds. Just make sure the glass clears.

I love the tire/wheel profile app you found.
It shows how this size does not change the outer edge of the tire or the wheel, and you should not have any glass issues, and the tire should give you the same profile/tuck from the outside.

Curious which wheel you found with this ideal size/offset?

 

im not sure how I would print that to scale. But I like the idea. Hardest part is getting weight on the car to simulate ride height.

not to worried about frame rub. With the factory YJ wheels and 255/60 rubber I was rubbing the paint off the steering box bolts. It was also hitting the glass wheel well on the driver side only so I was thinking of trimming that back. But these new tires are 8mm shorter and I loose 4mm off the one side so it might clear now. At full lock I was def rubbing on things in the driver side. Of course I’m running a borg box and and air ride support bracket which pushes the bolts out 3/16” due to the bracket thickness. I was looking at the lower Aarm steering stops last night. If I wanted to stop the rubbing I could Weld on some material to limit the travel. On my firebird with aftermarket lower arms I have adjustable steering stops to limit travel.

yea, that site is my favorite. I’ve been using it for like 15years. They just did an update a few months ago that improved the graphic so you can see the curve of the tire as it was just straight lines… it’s a nice improvement.

last question… I was measuring the wheel difference vs the fender edge and they are pushed out 5/8”-1” from the driver side to the pass side (sticks out 5/8” more on the front and 1” on the rear roughly). The bolt on spacers I have are 15mm but are not hub centric for the wheel but are for the car. If I put them on the driver front and rear I could match the pass side visually. And get me real close and add extra clearance On that side. Is it weird to do that? Would it cause any issues with steering or stress on the components if it’s just the one side? I would lose the wheel centric but then I was looking at them… I could weld them on the inside if I could align them up and then grind down the welds basically making them hub centric 15mm bolt on spacers for both wheel and hub then. I would likely test the look before doing it but I have let to fine anything that thin that has the correct 7/16-20 thread and have the correct 70.6mm hub. I’ve seen them in 70.3 but are 20mm and they won’t fit over the front hub I believe do to the design of how they machine the centric extensions part. On the rear it wouldn’t be an issue due to the axel hub stub being only 1/2” but the front cone could be an issue.

 

If your wheels tuck in different amounts on the right side vs the left side, it could be the body alignment.
There are six bolts that bolt the body to the frame.
And there are 2-4 alignment holes located in both, under the door sill chrome trim. Where the red plugs are.
Remove the door sill plate, the red plugs, and insert a large 12-18" drift pin thru the fiberglass hole and the frame hole that is underneath.
You can use that to both check, and adjust, the body alignment.

These things are basically just factory built kit cars, built by hand.
The bodies vary, sometimes a lot.
The high end restorations can go to great lengths to get correct panel alignment.
Sometimes they'll completely remove and re-bond the entire front clip, just for alignment purposes.
Ditto for front wheel splash shields, that affects hood alignment.
And I have seen hood skins pulled off their support frame, to get that perfect hood/fender alignment.
I know one car that had $60k worth of panel work, to correct panel alignment and body imperfections, before the paint.
It is the most perfect C3 I have ever seen. But really....

It's just a lot easier if you treat it like a street car, and not a Mona Lisa!

 

thanks for the tips on alignment. Not doing that lol. I had broken the front clip free to try and adjust the front clip door gaps. I had to rebond the front fender and actually cut the fiberglass and redo it. The car was in really bad shape but now it’s a nice looking car from
about 10ft. Even up close if you don’t know what Your looking for lol. The car probably has some frame damage based on what my dad told me and how much I have the upper SPC arms adjusted to get the alignment where I wanted it. That front driver wheel is also not really centered in the wheel well (favors the back side) the car drives good tho so I’m not complaining.

Last wheel came today so I loaded them all up in the truck to see if I can get them mounted and balanced near my job. Will report back once I get them installed and figure out what I want to do. Don’t want to hog the thread but appreciate all the help.

 

sorry I must have missed this. I went with ridler wheels. The 18x9.5 has a 5.25” backspace and 0 offset.

so I got the tires mounted and stayed up late to get them on the car for the first fit and have the car on it’s own weight on wheel Dollie’s so I can crawl under and test the front steering clearances.

good news is they fit. tight on the tire to trailing arm maybe 1/4” (Bridgestone has a thick sidewall ledge which offers nice rim protection). Sway bar is fine, 3/4-1” depending on the side. Clears the frame but tight on the driver side front frame. The spring bolts/washers are about 1/2” from the rim so they moved out as it lowered. The fronts are like 1/8” from the tierod, and close on the driver side to the back wheel well and hits the sway bar/front clip fiberglass support at full chock. Weirdest part (same with the stock wheels) is that the driver side wheels sits inward of the fender edge about 1/2” and the pass side sits about 1/4” past the fender edge. Im going to add a bolt on 15mm or 20mm spacer to push the driver side out to match for both wheels. I will loose the hub centric side on the wheel unless I can figure out a way to weld the centric rings to the spacers. obviously the spacers will give me even more
clearance from the front sway bar, rear frame and trailing arm. Might push it into the wheel well on the front driver on the backside of the tire more which is not great.


Pass side sticks out about 1/4” at tire side past the fender edge

Driver side sits 1/2” inward from fender edge at sidewall

 

Finally able to contribute photos I will get better ones eventually. Just got the car in the ground and it’s still dirty (tires are too). 78 that was converted to an 82 front and rear. Front bumper is a ACI custom. Car was in an accident and not put back together great 30-40 years ago with the previous owner. Front mods are stock lower arms cut 550lb springs, SPC upper arms. Rear mods are bilstein sports shocks, VBP 360# stock length leaf spring (not shortened), 8” van steel lowering bolts stock rear sway bar. I did relocate the parking brake tabs/cables.

18x9.5 front and rear. 5.25” BS and 0 offset
tires are Bridgestone potenza sports 275/40r18

pass side no spacers clears everything.

driver side front clears no spacers but I added 20mm hub and lug centric spacers so they match the passenger side. I got 20mm spacers with the correct 70.6mm ID hub and then welded 70.5mm to 83.8mm hub centric rings to make my own adapters. So the wheels are hub and lug centric all the way around.

 

Looks great!

 

Amazing work!
On the wheels I mean.

Oh and then there are those SBC mods too......

 

Thank you for your help! Love the way they came out.

 

The front sidewall has to come close the the rear but slightly shorter. I've got 10-18 265-40 and a 19-11.5 with a 325-30. Originally I had a 275-35 on the front ant the tire was too short even though that's the most one tire people put on the front most of the time. Picture as example.

 

I can now join the 18in Wheel party.

Now I have to do some body work on the front fenders to make it work right.
Krnc forged Wheels
L-88 Flares 4in back, 2in front
Nitto NT01's
315/30R18 up front with 4.5 inch backspacing
335/30R18 in back with 5 inch backspacing

You can see the cuts I had to make. Now to make it look pretty again and reshape fiberglass.

 

Cool wheels!