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Discussion Starter #1
I have searched alot of the old posts on wheel backspacing and tire size for 1968 camaro and have not been able to find a consistent answer on the topic!SO if someone out there could help give me a definite answer? Here is my question.i have a 1968 coupe with hotchkis 2" lowering springs on the front with drum brakes. On the rear i have hotchkis 3 packs.1 1/2" lower than stock.I will be running a 15x7 on the front and a 15x8 on the rear,l5x8 1/2" on rear if it will work? What size tire for the front and what size tire for the rear? and more importantly what back-spacing should i use front/back with no trimming etc etc.Naturally i would like to as much tire as possible If anyone could pleeeaase help me get the scoop!!! Thankyou in advance.I will be going to the tire shop tommorow to order wheels and tires or as soon as i can get some help with size.......
 

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Here is what I run on my '69Z with Hotchkis springs. I have front discs though.

Front:
15x8 4.5bs wheel with 235-60-15 tire
Requires buttonhead screws for the X33 wheel moldings.
I also run lots of negative camber for better handling and to get the top of the tire away from the fender.

Rear:
15x8 4.5bs wheel with 255-60-15 tire
The 255 tire is very tight - some guys experience rubbing on the fender lip depending on the rear housing alignment.
 

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Discussion Starter #4
Neil, thankyou for your reply. I'am under the belief that the 69 and 68 have different wheel-well openings.Again i do appreciate your reply.But if someone on this site that sees this message has a 1968 camaro or 67 and knows for sure what will work please let me know?
 

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MadCow, me thinks it's just not a good thing to post a definitive answer that one of our brother s will use to spend cash...

Too many variables, from car to car and setup to setup. The post at the top of wheels and tires has a lot of info regarding what people have made to fit, and it really depends on what you want and how big they gotta be
 

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Discussion Starter #9
Thanks Jim. I just want wheels and tires that fit.As best as i can tell from past threads a 15x7 with a 4-1/4" backspace for the fronts with a 215/65-15 bf goodrich and a 15x8 with 4 1/2" backspace for the rear and a 255/60-15.if you or another member has experience with this size tire/wheel combo on a 67/68 that has the Hotchkis sprngs on there car.please reply.I too am looking at spending some dough on rims.Thanks again in advance......
 

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fyi... my rallye's were 15x7, not sure of offset, w/ 215/65/15's all around and fit fine.

My new wheels are 16x7, 3 7/8 bs w/ 225-50-16 in front, 17x8, 4.5 bs, w 255-45-17 in back

Both sets fit great, naver rub, BUT... I don't have hotchkiss springs, and I have drum brakes in front. They all a lil different, ya know?

I think maybe a 7" rim w/4.25 bs might be too much, and rub on the frame when you turn sharp
 

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I just finished rebuilding the suspension on my wife's 68 convertible with hotchkis lowering springs. I am going through the same process as you are now. I also added SSBS's disk brake package, to the front only.
The original 14 x 7's that came off the car had a 3-3/4" backspace. I've borrowed a 15 x 7 wheel with a 4-1/4" backspace to mount and take some measurements. I'm assuming I need the wheel centered in the wheel well as much as possible. If I'm not sure when I order wheels, I'll probably go with more backspace than I think I need and shim, if I need to.
 

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There's a ton of info on here about tires sizes... but I guess if we didn't rehash it we'd have nuttin to do...

David, on your stock setup, the wheel would be offset 1/4" toward the inside of the car (from zero offset).

On a 67 or 68, the outside fronts can rub at the top of the wheelwell on compression, or the inside at the frame rail at full turn. This is all complicated by the stock alignment specs, and the suspension geometry, which lets the top of the front tire camber out on compression. (The guhldstrand mod, which I've done too, reverses that) On top of all that, stock disc brake cars shift the wheel a 1/4" out compared to drums, and with aftermarket brakes, who knows?

With the lowering springs, you for sure want an alignment before you start measuring for rubber.
 

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Discussion Starter #13
Thanks for you're response's. Jim What is the guildstrand modification exactly? As for the backspace issue i still do not have an answer!Does anyone Know!.....Dave if you could let me know how the 15x7 with 4 1/4 backspace works for you that would be great! I already ran a 15x7 with a 3 3/4 inch backspace and the 225-60 tire's rubbed both sides on the top of the wheelwell like you descibe Jim-but that would not jive with your 15x7's with no rub i'am guessing that your car was not lowered in which case it would not matter.maybe if you knew the backspacing that would help? Then there is still the matter of the backspacing on the rear wheels is the size that i'am thinking of running 15x8 with a 4 1/2 backspace a correct fit or can i go 8 1/2 with more backspace? anyone?...... :confused:
 

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No guarantee, but you want about a 25 +" tall tire, 235 or narrower up front on a 7" wheel with 4.5 bs up front (4" or less will probably rub and if you go with too short a tire (at 25" or less), looks come into play because of the round wheel well opening (even though you're dropped).

On the rear, I'd recommend 8" w/ 4.75" bs, 8.5 would be pushing it at 5" bs. (I'd bet you'd get rubbing) Tire should be 26" or taller, width 255 (max).

Again, looks come into play on the '67 & 68, see my post & pic under the top sticky.

I beleive if you stray from these, you better have a very tight suspension or you'll have to do well mods.

Let me know if something's unclear...

JD


JD
 

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I am a sick man, you got me running around with a straight edge and ruler in my jammies at 8am (lmao)

Before I forget, my original rallye's are verified at 15x7, 4"bs, w/ 25" tall 215-65-15 tires.

Look in Suspension, AND in DAVIDPOZZI's website for info on the Guldstrand mod. Basically, this is a real simple thing that road racers developed in the '60's to completely change the suspension geometry of a 1st gen. You relocate the inside pivot of the upper a-arm, about 3/4" back and 1" down. It changes the camber curve to keep the tires planted in turns, and builds some caster in.

I run 1/4 degree neg camber, it shifts to 2 degrees neg when the suspension compresses. Before, it shifted to 2 degrees pos! As compared to stock, this is moving the top of the tire over 1/2" further inside the fender when the suspension compresses!

I get 3.5 degrees pos caster, with almost no shims at all.

Tools required include a drill and a sawzall. It took me an hour, but the suspension was all ready apart. Cost is ZERO. Benefit is UNBELIEVABLE.

As for my ride ht... the rallye's were on the car when I got it, suspension was 35 years old and stock - no rub.

I rebuilt the suspension / did the guldstrand mod, and cut a coil off the original springs. Car was WAY LOW- no rub.

It was TOO low, so new springs, then new wheels and tires. Right now, the front fender lip is 25 1/4" off the ground, the tires are 23 3/4" tall - no rub, ever.

My rear wheelwell lip is 28 1/4" off the ground, tires are 25 1/4" tall. I have lots of room on the inside, over an inch. This is the first time I ever really measured clearance in the back. I've always thought my oem replacement 5 leafs were too high, seems it's a good thing. If my car was at the ht. I'd like it to be, the tires would be in the fenderlip by 1/4" Another 1/2" of bs would have been a better choice.

Ride and handling have been my priority with this car for 5 years. I'm on a pretty strict budget, so it's taken time. My car is a driver, and not the prettiest in the world. Before the ragtop, I had 3 new vette's in the '90's, so I'd like to think I'm experienced in what a good handling car feels like. My ragtop has become a good handling car.
 

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Discussion Starter #16
john why would a shorter tire rub? I also tried to locate the top sticky for the pic's but was unable to locate it.Jim and John and all the fellow Camaro Tech folks who responded to my post I thankyou
Jim you must be a car nut like my self and i greatly appreciate your patience and efforts in helping me!I will continue to post this topic when i finally put a tire/wheel set-up on my car and it does not rub, in the hope of helping other's. Madcow Mike....
 

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Good luck wit it, Mike. At least you came to the right place for the info.

As far as my 5 year suspension project, EVERYTHING I did came from here! Thanks to guys like davidpozzi, brian lewis, pdq, just to name a few... It's real hard to screw up when you can learn from all those who've been there and done that.

** If you haven't seen david's site, go there and spend a few hours... You'll learn more than you could imagine.
 

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Originally posted by JimM:
John, reading your post in that link, you got some outside rubbing in front... maybe a lil too much bs? I'd stick with 4"
Actually, not enough. I shoulda went with 4 5/8" or 4 3/4"

JD
 
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