Author Topic: 69 Z28 radial tires (Read 6983 times)

Danzo · « **on:** June 02, 2021, 10:27:51 PM »

Guys, looking to put a set of BFG Radial T/A's on a 69 Z28. going to use the stock 15x7's. What is the best tire size so there is no rubbing or any other BS. Stock suspension.
Thanks, Doc.

rich69rs · « **Reply #1 on:** June 02, 2021, 10:48:20 PM »

Might not help you very much since I have 14" rims on my '69 RS, but I have BF Goodrich Radial T/A Tires; size P215/70 R14 on my ride. They were installed in 2007 and have about 8500 miles on them now - no issues at all.

JohnF · « **Reply #2 on:** June 02, 2021, 11:23:57 PM »

P215/65/R15 is very close to the original E70-15
John

Gars68Tux · « **Reply #3 on:** June 02, 2021, 11:39:43 PM »

Yep, as mentioned, 215/65/15 is a popular choice if you want something similar to OE size.

Here's the spec sheet with dimensions. https://tiresize.com/tires/BFGoodrich/Radial-TA.htm

Hans L · « **Reply #4 on:** June 03, 2021, 04:02:32 AM »

Useful Tire Conversion Chart: https://www.errolstyres.co.za/vintage-car-tyre-conversion

Stingr69 · « **Reply #5 on:** June 03, 2021, 02:08:46 PM »

Good stock size recommendations here.

I know the more aggressive profile 245/60/15 will easily fit the rear but the front will rub slightly at the front fender extension. If you are willing to grab a small part of the front edge of the extension with a pair of pliers and gently fold it in about half inch it will clear. No paint damage or permanent modifications here.

If want zero contact you could run the 235/60/15.

william · « **Reply #6 on:** June 03, 2021, 02:34:53 PM »

Rally-Sports can have clearance issues at the left actuator bracket/shield.

z28z11 · « **Reply #7 on:** June 03, 2021, 04:01:59 PM »

Quote from: william on June 03, 2021, 02:34:53 PM

Rally-Sports can have clearance issues at the left actuator bracket/shield.

Amen. I've got 15 X 7's on the Z11, were on the car when I brought it home, rubbed horribly. I run 215/60R15 B.F. goodrich T/A's on it now, reasonable tire width, no clearance issues whatsoever. I like them as they are not obviously tall tires, more comparable to the lower profile Wide Treads. They fill the wheel openoiing better than the stock 14 X 7 YJ's - plus they don't rub.

Regards,
Steve

KurtS · « **Reply #8 on:** June 03, 2021, 04:06:07 PM »

Quote from: william on June 03, 2021, 02:34:53 PM

Rally-Sports can have clearance issues at the left actuator bracket/shield.

I've always wondered - what is different on the left side vs the right? I'd think that they were symmetrical.

william · « **Reply #9 on:** June 03, 2021, 04:28:57 PM »

Ackermann steering?

Back in the day it was common to see a hole worn in the left actuator cover. Could be we only noticed that on performance models with E70 & F70 tires. Those cars often had fast-ratio steering, which had 1º more angle at full lock than conventional steering.

KurtS · « **Reply #10 on:** June 03, 2021, 05:00:47 PM »

But both sides would have 1º more angle...
Something was asymmetric, somewhere.

Vince · « **Reply #11 on:** June 03, 2021, 08:15:31 PM »

When I had 235/60/15 radials on my '69 RS Z28 with 15x7 rally wheels the left front tire rubbed on almost full lock left turns and/or on uneven surfaces, but the right front never rubbed as far as I knew anyway. I eventually switched to E70 15 bias ply reproductions. No problem with them rubbing.

william · « **Reply #12 on:** June 03, 2021, 08:26:04 PM »

I believe the Ackermann theory is that both wheels cannot pivot in the same arc.

Possible the uca mounts are positioned to accomplish that; the left side is slightly forward of the right. The extra 1º of angle on N44 cars [and 70 series tires] either creates the problem or makes it worse.

KurtS · « **Reply #13 on:** June 04, 2021, 03:03:43 AM »

Yes, the inside and the outside front tires follow different radii. That's designed into the steering linkage. But there still should be symmetry.

Gars68Tux · « **Reply #14 on:** June 04, 2021, 07:25:12 AM »

The added weight of the driver (left side) ?

$:-\$

69Z28-RS · « **Reply #15 on:** June 04, 2021, 01:03:58 PM »

I replaced the actuator covers with GM parts when I purchased my car in 1976, and sure enough.. the LH side cover was rubbed by the tires on hard turns... Maybe driver weight?? who knows...

BULLITT65 · « **Reply #16 on:** June 07, 2021, 03:04:29 PM »

Intersting topic.For my white 69 RS Z, it came with 17" AR wheels. I put on a set of BFG radials on the original 15" rally wheels, and had a rubbing issue when turning on the right side. I swapped those when I found a good used set of wide tread GT, and thought that may solve the problem. Still have the rubbing issue, on a full lock but only turning left. After inspecting the car a bit I attributed it to a worn suspension, and it needing new bushings and possibly new ball joints with the amount of slop that is present. Could that may be the issue, with the rubbing on other cars as well.

Rufcar · « **Reply #17 on:** March 09, 2023, 10:26:24 PM »

I know this topic is 2 years old but anyway. I have run 235 /60 15s on the font and 235/70s on the rear of 10 years with zero issues. currently looking to go to all 60 series with amybe 2555/60s on the rear.

msbrunner@ucdavis.edu · « **Reply #18 on:** March 10, 2023, 01:00:52 AM »

I recently got a set of BFGs for my factory rallys on my ‘69 RS Z in 215/65. I don’t like the look as much as the bias-ply E70s as the 215/65 is smaller in diameter (plus of course a more square sidewall as a radial). If I got another set I would go for 215/70.

Sauron327 · « **Reply #19 on:** March 10, 2023, 03:57:52 PM »

Quote from: cruiserofland on March 10, 2023, 01:00:52 AM

I recently got a set of BFGs for my factory rallys on my ‘69 RS Z in 215/65. I don’t like the look as much as the bias-ply E70s as the 215/65 is smaller in diameter (plus of course a more square sidewall as a radial). If I got another set I would go for 215/70.

Coker sell radials that look like a bias ply.

Rufcar · « **Reply #20 on:** March 10, 2023, 07:09:02 PM »

I guess I was not clear: I have run 235 /60 15s on the font and 235/70s on the rear of 10 years with zero issues. currently looking to go to all 60 series with possibly 2555/60s on the rear. Can anyone give me any advice about these sizes? and possibly your thoughts?

msbrunner@ucdavis.edu · « **Reply #21 on:** March 13, 2023, 10:57:38 PM »

I run 255/60 BFGs in the rear of my Z on a 15x8 (4.5” BS) and it fits great. Not sure about fitment on the stock 15x7 rally in that size. (for reference these are BFGs modified by Diamond Back Tires to have smooth sidewalls)

Edit to my above post: the 215/65 BFG is the same diameter as the E70, at least unloaded. My mistake. The radial just looks smaller, something to do with the wider tread or sidewall shape I think.

Rufcar · « **Reply #22 on:** March 14, 2023, 07:41:45 PM »

Matt what measurements do you happen to have in your front and rear fender lip to floor? Jim

msbrunner@ucdavis.edu · « **Reply #23 on:** March 15, 2023, 05:01:32 AM »

Right now the fronts are 25 1/2” and the rears are 24 3/8” when on the BFG 215/65s on factory rallys. I have new custom springs on order from Coil Spring Specialties to drop the fronts to bring them level with the rears.

Rufcar · « **Reply #24 on:** March 15, 2023, 03:59:45 PM »

Tkx big help

Dave69x33 · « **Reply #25 on:** March 15, 2023, 04:23:23 PM »

When not showing my '69, I prefer the ride and handling with radials. I use 15x8 Corvette Rally rims (w/standard offset) with BF Goodrich 235-60 on front and 245-60 on the rear with no rubbing issues. NOTE: If you run old original front coil springs, they may have sagged over time and allow the front ride height to drop a bit. This was my situation which caused the driver's side front 235-60 tire to rub on the center (12 o'clock position) trim-to-finder bolt, during a sharp turn over a bump, or weight shift lean. New front coil springs corrected the ride height and solved the rubbing issue.

Rufcar · « **Reply #26 on:** March 18, 2023, 03:35:57 AM »

Those were the sizes I recently had in mine with the exception or maybe 255/60/15 rears. My front was never the problem even though they are sagged a bit but Im pretty certain my car left the factory as a 396 and Im running a 350 so that loss of weight cancels out the loss. I put new spring in the rear but I have those 70s back there the PO installed. going 60 to the rears will lower it 1 to 1.5". Im just not sure the 255s will fit but I see others have done that. Tkx

David K · « **Reply #27 on:** March 18, 2023, 04:13:23 PM »

I’m curious if this tire fitment thread works on any 1st Gen.

Rufcar · « **Reply #28 on:** March 18, 2023, 06:55:49 PM »

all cars in this discussion is for the 1st generation.

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Author Topic: 69 Z28 radial tires (Read 6983 times)