Another BFG 235/60/15 QUestion - Team Camaro Tech
Wheels & Tires What fits what?

 
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post #1 of 3 (permalink) Old Jul 19th, 08, 10:37 AM Thread Starter
MrBob
 
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Angry Another BFG 235/60/15 QUestion

I have a 1980 Z28. 350/350. I believe I have 15x8 front and 15x10 rear. 295/50/15 rears and I had 215/65/15 on front of my car that would just rub on severe dips/turns. wasnt thinking about this when I started replacing tires. after reading a bunch of tire size stuff, I went with BFG T/A 235/60/15.

You would think the Tire shop guys would have said something, but I see other guys running this same tire. I cant even make a slow sharp turn without major rub. I think the inside of the tire is hitting the rear of the front fender, secause once I get past a point the rub stops. I dont even want to talk about speed bumps or dips. I thought the front end of my car was about to shread my tires on the highway at 65MPH when I hit a big dip and felt like front wheels locked up.

Of course the tire shop wont do anything because I asked for the size and there are people using this same wheel/tire combo. when I look at the wheel in the fender well it looks like both front tires are back too far. Maybe 1 1/2" or less from tire to rear of well and 3"+ to the front.

The shop told me I can not adjust the position on these, but I can buy a new adjustable "??" to be able to adjust the wheel forward (alignment)

After reading a bunch of posts on here, I already plan on getting BBC springs and new shocks, etc.

Can anyone tell me what part the tire shop is talking about? I have searched for various front end parts, but have yet to find anything to adjust the wheels forward...

Am I just looking at wearing out these tires and going back to 215/65s?

ALSO on a side question, I am thinking of going to 295/60s on the rear to get about 2.25" more diameter (there is plenty of room in the back well. Does anyone have any rear tire suggestions?

Thanks to you all...

MrBob

Last edited by mrbob111; Jul 19th, 08 at 11:35 AM.
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post #2 of 3 (permalink) Old Jul 19th, 08, 03:57 PM
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Re: Another BFG 235/60/15 QUestion

Bob,
I answered your question on another post and in PM...

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post #3 of 3 (permalink) Old Jul 20th, 08, 01:06 AM
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Ron
 
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Re: Another BFG 235/60/15 QUestion

I really don’t know what to say, other then it takes patience and ingenuity. If you have a theme you want to express you have to spend hours measuring before you commit to modifying a car. Not every persons idea of sculpture is the same as another’s but if the concept is accurate your art will be admired.

Not too many cars will accept the all out mean muscle look of the 70 to 73 2nd GEN models The main reason is that they where built simple and not as refined as the later models. I'm not that familiar with the 80 model but I can’t see it being that much different other then as I say; Refined". The sub frame and the control arms are specific for the 70 and fitting P235 60 15’s on Vette 15 X 8 Rallies was conceivable after lots of measuring and pondering. I can’t over stress how important it is to line up the sub frame. Move it forward as much as possible ¼” can make a big difference. Ensure that the frame is accurately in position before you torque the frame mount bolts. Use a solid mount on the rear sub frame and install Sub Frame Connectors. Sub frame connectors are essential to keep the sub frame in position, keep doors aligned, prevent the sail skin from cracking ...etc.

I do not know what rims you have chosen but off sets are very important. I managed to fit P235’s on 8” Vette Rallies on the front of my 70Z but it was not without work. The Vette Rim sets the tire out considerably more then Camaro rim. It adds that full wheel look which I wanted to achieve. Here are the matters that I had to contend with to make them fit; that is find the clearance to prevent the wheels from rubbing on the lower back of the wheel well were the fender bolts to the tub. As mentioned, it is pointless attempting this without securing the front sub frame. The doors must fit with a perfect 1/8” spacing to the rear quarter so that the front fenders and consequently the whole front clip can slide back to close the front door skin gap. After all that work I still ended up with a rub in that area after but it was considerably less. I recall the driver’s side was a little worse then the passenger side but that may only be specific to my car. I dolled in the passenger side stretching the metal and pushed it back. The driver’s side I had to cut a “T” like line in the area of contact in order to push the metal of the tub back enough to clear and weld in a small patch. I used low profile bolt heads on the 2 lower tub bolts supporting the fender lip. You might have to roll the fender mount tab in a little as well.

I believe P295 N50 15’s on 10 rims will fit in the rear wheel wells but not using the Vette Rallies because they position the tire out too far extending the tire beyond the wheel lip. They will be impossible to use because the tires will strike the upper wheel lip. A rim with the correct off set should work to move them in and clear the outer lip. There should be lots of clearance to the leaf springs and inner tub. However there is one problem that this creates; and that is, it greatly limits the clearance necessary for Dual Exhaust Tail Pipes. Using the Vette rim gives you plenty of room for tail pipes but if you choose this route you have a major reconstruction to do on the rear wheel well lips. I choose to use the Vette rims and modified my rear quarter panels. This modification was very popular in the early 70’s and reflects the era but it’s not easy for anyone without body experience and very costly to pay a shop especially if it is to be done correctly. I really can’t say how this mod would look on an 80.

Stance and Rake is what your after. The P295 N60 15 is not that much higher if not the same diameter as the P235 60 15. Raising the rear end of the car just the right amount is critical to achieve rake. In my case it gives me additional clearance for rear wheel travel with out hitting my wheel flares. How do you achieve this? It was common for people to use longer rear spring mounting straps. I believe they were called "Rear Leaf Spring Shackle Extenders". I required a 1½ inch lift, not much you might think. Now consider the work and modifications. I don’t care for extensions as this affects the handling specifically cornering. A Z28 is designed for road racing not ¼ mile and that I want to keep original. Here’s what I did to increase my rear lift by 1½ inches. I had the main rear spring re-arched and installed new springs adding an extra leaf. The extra short leaf is short and used as a plate to control the tension of the rear springs and consequently adjust the ride height. To make the system work, I removed the rubber mounting pad and welded in a 3/8” plate with a centering hole for the spring perch. I made ½” steel plates that fit over the original lower retainer plates. I made new brackets to mount the sway bar which mount to the longer high grade axle “U” Bolts. By varying the torque on the inner bolts and “U” bolts securing the axle I can effectively change the spring rate and ride height to a certain extent. Of course lowering the rear axle 1½ inch leads to other modifications. I had to extend the Sway Bar rods 1½” and install a longer flexible brake line hose. One from a Ford pickup suited my needs. I also had to use 1 1/2 inch longer rear shocks. Shock extenders would suffice in this case.

I hope this gives you some insight and idea’s on how to approach the task of installing large wheels and have the car look as if it were designed to have them ))

Here’s some PIC’s:











These pics don't really reflect the true stance because I happen to have over 600 lbs of parts in the trunk and rear seat. I was off to a swap meet that day.

Quote:
Can anyone tell me what part the tire shop is talking about? I have searched for various front end parts, but have yet to find anything to adjust the wheels forward...
I would imagine they are referring to adjustable Upper and lower Control arms. There might be a hub carrier product with off set spindle and brake mounts.

Z15CAM - There was a Viper in my Rear View
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This was my 70 1/2 Z28

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Last edited by Z15CAM; Jul 20th, 08 at 05:13 PM.
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