Pontiac GTO Forum banner

1 - 20 of 23 Posts

·
Premium Member
Joined
·
58 Posts
Discussion Starter #1
Hey guys, I'm seriously thinking of going to the Firestone G70 bias tire route, yes to get the look and to achieve the right height.

Currently my 69' has radials.

I get that the bias tire won't run as good as a radial but how big is the difference? Is it like going to a Flinstone's car? Or tractor?

I bought an old car because I like the old car smell, feel, power, and don't need the car to drive for me. So unless I am going to be all over the road and cutting people off mistakenly I don't see an issue?

Would appreciate any comments on you're experiences.
 

·
Registered
Joined
·
3,785 Posts
Here is my opinion and what I recall, but that was a long time ago, so others should chime in on this.

I know bias ply tires make a better smokey burn-out! I remember when the radial was just hitting the market - I was a kid driving then. I remember they were really expensive and there were rumors that the steel belts could break or slip within the tire, but with all things, improvements followed.

Radials lasted longer and did handle & grip better under most conditions - due to a thinner sidewall that puts more tread down on the road as it flexes. I remember that although radials gripped better, in a "take it to the limits" high speed corner, they would not give much warning when they were on the verge of breaking loose. Once you heard tire squeal, you got ready for the car to get a little sideways -and I don't think they recovered as well at that point of breaking loose. Bias tires seemed to squeal to give you a warning and could be pushed a little more until the tires actually broke traction.

Bias tires always seem to offer more "squeal", lots more smoke, and a nice black (or two if posi-traction) strip of rubber on the pavement that can last for months in a good long burnout. Done right, you can engulf your entire car in a cloud of tire smoke and impress your buddies! Radials "squawk" or "chirp" and then spin, don't throw off much smoke, and seem to leave a faint black burnout strip of rubber as you're melting the hides. And that's what I miss about bias tires.

If you do a search on the differences, they are explained. Bias tires have thicker side walls and less flex, they hold heat more, and are less fuel efficient. They also have a different side wall height that radials don't (especially these newer metric designated tires).

They came on the cars originally. I drove bunches of cars with them to include my old GTO's and other cars. Never had any problems and I did not baby my cars and always pushed them and would light up the tires whenever the mood hit - which was often.

Yep, you may find yourself having to "drive" the car a little more. If you get them, I would just pay attention to how the driving and handling will change a bit from what the radials offer, and adjust to it. Might try some hard cornering in a safe place where no damage to car/driver/others will occur just to get a feel of it. I would also pull a couple hard accelerations to experience the tires breaking traction as well as hard braking. Once you get a feel for it, then adjust your driving to know what to expect.

If you do switch to the Bias-ply, it would be neat for you to come back and write your experiences as to the differences you noticed before and after.
 

·
Registered
Joined
·
2 Posts
Bias tires for GTO

When I bought my GTO twenty five years ago it had bias tires. I drove on them a few years and finally got red line radials. I personally wouldn't have bias tires. If you get in a rut in the pavement it follows that rut. The ride was so different in bias versus radials. I know people who want that vintage look but I would rather have a nice ride verus all over the road. Just saying.
 

·
Premium Member
Joined
·
58 Posts
Discussion Starter #4
Great write up PJ, I'm in the midst of a mild resto but I've been gathering parts like crazy! The engine is out and stripped and soon the front end is coming off. I decided to go with the Butler 467 kit... Yikes!
The tires are a ways away but trying to do my research before I pull the trigger. If I do get them (which I'm leaning towards) I'll post the results for sure.
 

·
Premium Member
Joined
·
23 Posts
If you really want to enjoy driving the car, go 17" Rally II. 275/40R17 front and 285/40R17 rear. Continental Extreme DW. I have that combo on my 68, 70 and 71 GTO convertibles.
 

·
Premium Member
Joined
·
58 Posts
Discussion Starter #7
Thanks GMP I've seen the 17"s and they do look sweet but I'm trying to keep an original look.
Your in the tire biz... So does that mean you've driven radials and bias? Or just heard back from some guys saying the bias tires I bought from you suck?

I don't need to take a corner at 70 mph to feel cool... I'll leave that for the drifting guys.

BTW my front end suspension is fully rebuilt and right now (or did) the car drives awesome!

Are they over priced? Probably. Do they REALLY drive like crap?
 

·
Premium Member
Joined
·
23 Posts
I'm 59 years old. Bought my first GTO in 74 when I was 17. A 68 convertible of course it had bias tires. I'm a lucky guy. I have seven GTO convertibles now. I drive them all like I stole them. I have a friend who had bias tires on his 69 GTO convertible. When I drove his car I was shocked at the difference. Bias might look cool for show. But only if you're trailering the car.
 

·
Premium Member
Joined
·
58 Posts
Discussion Starter #9
Thanks gmp, I appreciate your insight. I guess to really find out Id have to buy a set and then say oh man I should have stayed with radial!
Lol.
Shows and cars are starting to pop up around this neck of the woods so I'll see if I can drive something with bias tires and a similar build.
 

·
Registered
Joined
·
440 Posts
Thanks gmp, I appreciate your insight. I guess to really find out Id have to buy a set and then say oh man I should have stayed with radial!
Lol.
Shows and cars are starting to pop up around this neck of the woods so I'll see if I can drive something with bias tires and a similar build.
That's the smart thing to do. I put F70 repos on my '67 many years ago for the correct look. My front suspension wasn't the best (it still isn't) but I felt like I was riding on potato skins. Put BFG 235/60R15's with the letters turned inside. Much better feel. They will break loose if you tromp on it just right.
 

·
Registered
Joined
·
773 Posts
I favor the steel belted radials and do remember the bias ply tires ride. All great and accurate comments here. IMalways felt the wander in bias ply tires, the faster you go the more they wander...you can tell easy at 70 mph...less at 30...just put a set of cooper Cobras 245 60 R15 on my 66 lemans...and some Continental 265 70 r 17 on my PU....

Well balanced both ride and look great....original looks for show originality would be bias....

Driving it....get some steel belted radials, they ride better because of the tire technology and the steel belts do sometimes repel sharp objects a hair better....less flats are a good thing...:nerd:
 

·
Premium Member
Joined
·
58 Posts
Discussion Starter #12
Thanks for the insight guys. Considering the engine build is consuming most of the funds I'll put the $1,100 for bias tires towards something more important. :grin2:
 

·
Registered
Joined
·
1,611 Posts
Have driven many older Pontiacs with bias ply Firestones and Goodyears. G78-14's , G70 and H70x14's, F60x15's. On the typical asphalt roads around here, even a well aligned vehicle with like new front end parts when equipped with bias plys, the car will tend to "hunt" through the troughs of the road surfaces. To many, esp those that grew up on radial tires, this is very annoying. For years, many of us ran Eagle ST's as a good looking radial alternative, but they dried up new many many years ago.

For my own keeper Pontiacs, have a combination of NOS and reproduction bias ply G70-14 and F60x15 Goodyear Polyglas tires. The reproduction Polyglas tires are made of a slightly different compound than originally, and in a properly set up vehicle will hook up well at the strip. Rusty Small is a great source for discounted new PolyGlas G70-14's, G60-15's. Rusty posts on V8Buick.com in the PureStock forum, as well as on PY, and I'd bet a few other forums. From east of Kansas City where he lives, to dropoffs at the Pure Stock Drags in Stanton, MI in mid Sept, Rusty provides a good deal, on what have become quite expensive repro tires. Not into the stock look and hook, there are always rock hard T/A radials, Coopers and hankook radials or you can go whooptee with 17's, 18's, 20's.
 

·
Premium Member
Joined
·
58 Posts
Discussion Starter #14
Hmmm, I gather bias are stickier than radials not like slicks but somewhere in between?
I did end up rebuilding my 8.2 rear end with an Auburn pro posi unit. I wonder if the radials would offer say better slippage under high torque situations as to safeguard the rear differential. May sound a little crazy but I am somewhat concerned about the diff considering I went the stroker route with my engine. Mistakenly I rebuilt the rear end before I decided on the engine.
 

·
Registered
Joined
·
1,611 Posts
The bias ply repro PolyGlas and Firestone Wide Ovals are expensive and don't behave that well on typical road surfaces on a driver. iMO, they're good for two things:
- cars being judged at high level, usually, national shows,
- events like the Pure Stock Drags. when one get these repro low profile tires hot, they stick pretty good.

the latter said, with over 500 fts of torque, one has to get them hot and ease them off the line, or they go up in smoke. On your GTO, with a healthy stroker engine combo, and a gray iron 8.2 Pontiac rearend hsg, getting the rear tires to hook really well is going to test the limits of the pinion area in the gray iron housing. IF your '69 GTO came with minimum of a 3.55 Safe-T -Track, the front of the nodular iron housing will exhibit less movement under high loads. i don't build off the Pontiac 8.2's much, as the 8.5 Abody housing has much more pinion support and HD parts availability has been much higher with the 8.5 for decades.
 

·
Premium Member
Joined
·
58 Posts
Discussion Starter #16
Appreciate that PH, I'll stick with the radials on the car as it is not a show or concours resto, comments lean towards radials. I should be driving by next spring... At the rate I'm going.
 

·
Registered
Joined
·
22 Posts
I am thinking about going the same route with my 69. I thought that I would go with 15x7 rally's and G70's. I would like to go with the bias ply because I like the look too. Does anyone know about the fitment issues with the 15x7's versus the 14" rally's? I have the BFG's now and the car drives great but I would like the bias ply look. I don't drive the car too far since it has a 4.33 factory rear gear. I am following the discussion and the content is great. I have never driven on bias ply's either.
 

·
Registered
Joined
·
3,785 Posts
Not trying to beat a dead horse or convince anyone of which tire type to use, BUT.....

I have to say that the bias-ply tire might respond better with regards to a radial tire IF the suspension/handling is improved. Radials really did not come on the scene on a large scale until mid-1970's. Even then, the suspensions were "tuned" to use the radial tire - recall the RTS (Radial Tuned Suspension) that came out on Pontiacs in 1974. I have read that radials should not be used on cars that were not designed for radials. Of course I have used radials on my older cars and had no ill effects (that I noticed), so I don't know how true a statement that is but I did find a mention of this and a comparison here: The Right Tire for Your Classic Car

That said, keep in mind that many of the best, and our favorite car movies had cars using bias-ply tires and the proof is in the pudding. However, as stated earlier, I am sure we can all agree that these cars had modified suspensions to handle the moves these cars made. So how bad could the bias tire be? Maybe its all in the suspension to make 'em work better.

Bullitt - 1968
Dirty Mary & Crazy Larry - 1973
Vanishing Point - 1971
Gone In 60 Seconds - released in 1974, made during 1973
The Seven-Ups - 1973
McQ - 1974 with 1973 Trans-Am
The California Kid - 1974 TV movie release, car built in 1973
 

·
Premium Member
Joined
·
58 Posts
Discussion Starter #20
Great info here guys! Thanks.
I think I'm going to stick with radials, it seems the bias tire route could be an expensive disabling of the the driving quality.
 
1 - 20 of 23 Posts
Top