Stock Tires on Clamshells from 71-76; Bias Ply or Radial?

I'm curious if the stock tires changed from bias ply to radial some time in the 70s. I heard that the 1973 Oldsmobile Custom Cruiser that Hullinger bought had Bias Ply tires when he bought it.

 

That's a good question, as the changeover with all the American car builders did occur during the decade. However, I don't know if the government mandated a change date or even year. But I remember that a lot of cars were advertised as receiving radials from the factory.

 

Radials started becoming common from 73-on, and I believe 73-74 is when you began to see the Radial Tuned Suspension dashboard emblems on the Pontiacs. I don't care what year the car is, Radials will make a big improvement in the ride and handling on these big wagons.

 

You could get radials as an option on my 67 Electra, so I would say most of the big wagons of the 70's had them from factory.

 

One way to find out--the tire placard in each car. Of course, any car with radials as option or standard, the tire size has an 'R' in it. Babe's original tire size from the factory was the HR78-14.

 

Thanks for your valued replies, everyone. I should say why I'm interested in this: I wondered which year and make of Clam wagon I'd buy in its stock form if I was looking for one to drive and I don't feel like using Bias Ply tires which I have no experience driving on (I also read Bias Ply tires "handle like a pig on stilts" if that's accurate.) It would be interesting if the government mandated Radials for 1974 models along with the emission equipment.

Hmm...

Turns out with a little Googling there's this article from the New York Times in 1981:

"...The big shift to radial tires began in 1974, when American car makers began making suspensions specially designed for the longwearing, gas-saving radials. Goodyear said the percentage of new cars having radial tires as original equipment jumped from 19.2 percent in 1973 to 43.9 percent in 1974."

http://www.nytimes.com/1981/08/27/business/radial-tires-for-us-cars.html

I see that's after the gas shortages of 1973. The big question now is, does "1974" in the article refer to the model year or not? I suppose the 75 and 76 Clams might be the best bet for having Radial Tuned Suspensions. And hey, that leaves at least one year for the large G.M. convertibles too (I can dream. Hmm, I wonder if Grandpap ever owned one of those.)

 

According to the Olds dealer specs books, the '71, '72, and '73 Custom Cruisers came standard with blackwall, bias-ply tires. Optional was a white sidewall, bias-ply tire. No mention of radials.

The '74 Olds brochure mentions, in the "new for '74" section, the availability of radial tires. They were optional on all models except for the Cutlass Salon, on which they were standard.




The '75 Olds brochure mentions radials as standard equipment on all cars.

 

When getting my first '55 Chevy sedan ready for a road trip from Illinois all the way around Lake Michigan I noticed with like new tread the like new side walls of the bias ply tires were so badly age cracked I could almost see the air inside.

I had just bought new take off radials on S-10 rally type wheels for my '55 wagon. Thanks to my wife at a yard sale!
Temporarily I put that set on the '55 sedan with stock suspension yet 350 and BW 4-speed. No upgraded suspension.
Before the tire swap the'55 sedan would wander and shimmy on a certain diagonal RR track in town and would "handle like a pig on stilts" other times.
Just the simple wheel and tire swap made the '55 Chevy handle more like a late model car and became a pleasure to drive. Those radial tires remained on the sedan for years.

 

Thanks, good to see these scans. Is this similar for Buick, Chevrolet and Pontiac?

 

I didn't check Pontiac and Buick. Chevrolet was identical to Oldsmobile. Bias-ply only through 1973. Bias-ply standard with radials optional for 1974. Radials standard equipment for 1975 and later.

It would surprise me if Pontiac and Buick were not the same.


From the '75 Chevy wagon brochure:




From the '74 Chevy full-size brochure, standard equipment:




'74 Chevy full-size brochure, optional equipment:




It's interesting that this says that, if you bought radials when you bought the car new, you also got a "radial-tuned suspension and steering components to match." So what would happen if you had gone with the standard, bias-ply tires initially and then decided later on, when it came time to replace the original tires, that you wanted radials? Would you have been advised not to do so? Or would it have been acceptable to put radials on a non-radial-tuned suspension? Also, how do you tell now, in 2017, which suspension is on a 1974 full-size Chevy as it most certainly would not still have its original tires.

 

I'd like to know what the "radial tuned suspension" was. seeing as how all the front end parts interchanged 71-76.
I will check my placard on my 71 Mark III pretty sure it came with radials

 

Yes, how could we tell if it's equipped with this "Radial Tuned Suspension" or is it just marketing speech? The primary reason why I'd want a 75-76 model (or maybe a 74, depending) is if it has this "Radial-Tuned Suspension" which I'd guess should handle better than the 71-73 models.

 

Radial tires came out on some Pontiacs in 1973 (like the Grand Am, Bonneville, and Grand Prix if you checked the right boxes) and was more common in 1974, with I believe 1975 it becoming a standard for all new Pontiacs. The "radial tuned suspension" on big Pontiac cars for 1974 was listed as "all models" while 1973 was only for the Bonneville, which was not part of the station wagon lineup at the time.

 

I think the Radial tuned suspension was much like the " Wide Track" in later years
Sales point

 

I have to clarify that I was wrong... radials were not an option. I got confused because for judging purposes, radials on my car is not a deduction because radials were available in 1967 for the car. Sorry for the misinformation