1. Hello there guest and Welcome to The #1 Classic Mustang forum!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Differences in e.t.s between bias ply and radial tires?

Discussion in 'General Mustang Discussion' started by RagTop, Feb 2, 2017.

  1. RagTop

    RagTop Old Grumpy

    I subscribe to Muscle Car magazine and they publish specs on almost all the cars they review. Unfortunately, most of the quarter mile times and trap speeds are from magazine reviews in the 60s when the cars were new and they were all running bias ply tires. Many of the muscle cars in those days ran high 14s and low 15s in the quarter with speeds in the high 80s and low 90s. The cover car in this month's issue is a '66 Chevelle Malibu SS 396 360hp with the good old Muncie M21 close ratio 4 speed and 3.31 gears. The magazine times from back in the day said 15.50 @ 89 mph. That just blew me away since my 302 Mustang with very minor modifications, a C4 with shift kit and 3.55 gears has posted a best of 14.308 @ 99.1 mph. How much of a difference do you think bias ply tires made?
     
  2. Mach1 Driver

    Mach1 Driver Active Member

    The bias belted tires wouldn't climb over a imperfection in the road- like where an on-ramp meets the freeway- they would tend to be steered to the right and not want to climb over a ridge. Its just a guess but I would think that it has much more to do with today's tire compounds and tread patterns- they're just stickier.
    Back in the day my ol' Stang would smoke all the way through 1st, hop through second, and get maybe 20 feet of scratch in third before it finally grabbed. It was fun to drive, but it wasn't fast, it just didn't have any traction and gave the impression of speed. It has 77k on the odometer and everything is still stock and it will barely chirp today's tires. Its a 351w 2v with an FMX. OK, the octane is now 97 instead of 102 and that is a noticeable difference. I still think its the tire compounds.
     
  3. KBMWRS

    KBMWRS What did the moron say today?

    Its the driver, Ken. You're just that good.
     
  4. Midlife

    Midlife Well-Known Member Staff Member Moderator

    It's probably not bias-ply vice radials, but the tire compounds are so much better these days. You can get them very sticky, with low mileage warranties, or low rolling friction with high mileage warranties. Back in the days, bias-ply with state-of-the-art compounds would last maybe 15k miles. Tires now can last 70k.
     
  5. msell66

    msell66 Road Worthy

    What is this world coming to? I've agreed with Gary AND Randy in the same day!
     
    tarafied1 likes this.
  6. Horseplay

    Horseplay Well-Known Member

    I would throw out though that most of those drag runs were with professional drivers who would get the most out of the cars. Tracks were/are prepped to aid in traction so while today's tires are much better it wasn't as bad at the track as it is on the street. Also remember, the power ratings of the day were a pot luck of BS and mild science. Many times understated and often embellished. A quick Google search showed test times by all the popular car mags with 1/4 times between 15.5 and mid to upper 14's. With a driver that car, with that engine, weighed in at close to 3800 lbs! That's a heavy ride . You in your car are 800 lbs or so less in weight. That's about a full second off ET right there.
     
  7. RagTop

    RagTop Old Grumpy

    Clearly you've never met me. I add considerably to the curb weight of my Mustang.:) Whether it's tread compounds or ply configuration, no one seems to be able to comment on the eventual impact on e.t. results. I'm pretty sure no one has ever tested the same car with radials and then made passes with bias ply tires, but it would be an interesting experiment. I frequently hear "Yeah, but that was on bias ply tires." as an explanation of the differences in e.t.s but no one can define what the size of that difference is. This has nothing to do with following road seams or track handling. We're talking pure traction.
     
  8. msell66

    msell66 Road Worthy

    Hmmmm, I have sets of both types......
     
  9. RagTop

    RagTop Old Grumpy

    Sounds like you might have the necessaries to answer my original question. All you'd need to do is change out the rear tires. Probably make several passes on both sets to establish an average e.t. for each.
     
  10. RagTop

    RagTop Old Grumpy

    Snarky Mike, snarky.
     
  11. KBMWRS

    KBMWRS What did the moron say today?

    Ken you should check out the drag series called FAST...Factory Appearing Stock Tires. The engines can be internally modified but tires are stock bias.
    http://www.fastdrags.com/
     
  12. RagTop

    RagTop Old Grumpy

    Interesting reference. Kind of puts my Mustang's performance in perspective, but it still doesn't speak to the issue of same car, stock or not, on both radial and bias ply tires. The comparison would have to be done with the same car on the same track on the same day. Sounds like msel66 might have the materials to conduct that test and quantify the delta.
     
  13. tarafied1

    tarafied1 Well-Known Member

    I was thinking about that series too but I am willing to bet there is some hokey pokey going on with those tires. Have you seen the times they are running? A couple have broken into the 9's. No way an off the shelf bias ply tire could run that quick, AND some of the pics show cars lifting the front end. They have to be taking a belt sander to the inside of those tires and soaking them in glue or something...
     
    Last edited: Feb 3, 2017
  14. msell66

    msell66 Road Worthy

    If I can get the car back on the road and the snow goes away......
     
  15. RagTop

    RagTop Old Grumpy

    Yeah, drag racing in the snow can be challenging.:) You could always do a "with and without chains" comparison.
     
  16. RagTop

    RagTop Old Grumpy

    Actually, I was thinking the same thing. The same magazine, Hemmings Musclecar magazine, frequently has articles about stock muscle car drags with pictures, e.t.s and trap speeds. Most of the 60s-70s muscle cars are posting times in the 12s with some into the 11s. There are lots of pictures of guys with things like Falcon Sprints lifting their front wheels. Having been a drag racer in the early and mid 60s, I will officially call B.S. on those numbers. Guys who cracked into the 14s and over 100 mph in stock classes were considered real badazz racers back then. My C/Stocker (which was anything but stock) was turning in the mid 15s and low 90s at Fremont Drags back in the day and winning it's share of trophies.
     
    Last edited: Feb 6, 2017
  17. KBMWRS

    KBMWRS What did the moron say today?

    Really Ken you were in drag? I think there is a more politically correct way to say it now.:rolleyes:
     
  18. RagTop

    RagTop Old Grumpy

    Mike, to quote a late president, "There you go again". What's up with you? Is that the most constructive thing you have to add?
     
  19. KBMWRS

    KBMWRS What did the moron say today?

    Yep.....hey all I do is check SF every morning....Hey I told you about FAST races at least.
     
    tarafied1 likes this.
  20. blackford

    blackford Member

    That car was not that heavy. New cars are heavier than old cars were. They are crammed full of so much safety, electronic, etc equipment than old cars were and they are bigger than old cars were. New Mustang 3600 lbs, new Camaro 3500 lbs, new Challenger 4000 lbs! 66 Chevelle 396 3300 lbs. We've gotten used to big cars and don't even realize it. They don't seem it but pull an new Mustang next to an old mustang or a new Camaro next to an old Camaro, and many other examples. Someone even mentioned how my 65 FB and a 2 door Mini Coachman wasn't much of a size difference...the Coachman weighs more.

    The bias plies were part of the problem and the skinny width of the bias plies were also a problem. Old Muscle cars would roast them and off the line was more like feather it to get it going and then nail it. Young people think old muscle cars were slow based on crappy 1/4 mile times. They were a lot faster than they think and a bit of tweaking here and there from the factory (headers, intake, carb rejet, ignition) and they got even faster. Even so, they weren't as fast as cars today, but faster than people think.
     
    Last edited: Feb 22, 2017
    msell66 likes this.

Share This Page