bias ply fronts / drag radial rears

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Kbails
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bias ply fronts / drag radial rears

Post by Kbails » Wed Nov 08, 2017 7:24 am

hey currently run radial tires front and back. mickey 275pros in the rear and a passenger car radial in the front. my car is now trapping around 130 and I want to purchase new front tires. has anyone ran a bias ply front runner and radial rear? I was told not to do this, as well as somebody from the ''tech'' department at mickey Thompson says never to mix the 2. anybody that has done this or opinions on if you should or nont let me know. thanks
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GRTfast
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Re: bias ply fronts / drag radial rears

Post by GRTfast » Wed Nov 08, 2017 8:56 am

I've always heard that the issue is the way the different tire constructions handle imperfections in the road. I imagine that if the car is used only on the track, it would probably be ok, but there is no way to really know without trying it. My dad's 8 second altered had bias ply slicks on the rear and low profile radials on the front and never had an issue. I'm sure someone else with more knowledge can weigh in.

tresi
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Re: bias ply fronts / drag radial rears

Post by tresi » Wed Nov 08, 2017 9:43 pm

Back in the 70's and 80's tires shops used to have posters warning not to do this. Most everybody in this time period has probably bought a used car that had mixed tire types. I never noticed anything but I never set out to try a high speed test.

Kbails
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Re: bias ply fronts / drag radial rears

Post by Kbails » Thu Nov 09, 2017 11:17 am

ok I talked to few more people and did some digging and got a few different answers. the main answer I got was. check out the radial vs. the world cars they all run bias fronts and radial rears. was also told that this whole myth that you cant its nonsence and as long as you have tires matched on each axle you will be fine. one web article had quoted a m/t rep stating that this is fine and nothing to wory as long as axles are matched. any input or real life experience with this?
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Speedbump
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Re: bias ply fronts / drag radial rears

Post by Speedbump » Thu Nov 09, 2017 3:30 pm

I have done it on a street driven car and can guarantee you feel the difference on a well travelled road where there are "ruts" where most people drive. One tire(stiff sidewall bias) will try to crawl out of the rut and the other(more flexible sidewall radial) will try to conform and go straight.
At freeway speeds it can be a very uneasy and sometimes dangerous feeling. That being said, a drag race rear bias tire has, by design, a very flexible sidewall and most tracks are smooth. Probably not a problem there but when I chose the fat rears for my 55 pro street build, I went with Hoosiers because they were radial construction and MT's were not and I knew I would run radials on the front. Maybe that's why the MT guy said what he said since up until a few years ago, their fat Sportsman and Pro Sportsman tires were all bias ply.
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chimpvalet
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Re: bias ply fronts / drag radial rears

Post by chimpvalet » Sun Nov 12, 2017 6:14 pm

Well, there's radials and there's radials nowadays. Winter radials are constructed to offer soft sidewall compliance for better resistance to letting go in lateral loads, and to me feel like the Michelins we fitted to the family grocery getter decades ago. Summer or 3 season radials have had much done in terms of their construction to stiffen for side loading in order to sharpen steering response and keep the tread on the pavement at higher loads. Had a beater '80 Cougar 302 with Monroe GP shocks ( stiff ) running 55 series modern radials that got real spooky when I tried to fit a set of winter radials to the back axle only. Merging onto the freeway at normal speed had the car go into a downright creepy corkscrew sort of yaw when crossing over wear ruts in the asphalt. Went to winter radials all around and have done so ever since, so the takeaway for me is that differing sidewall characteristics end-to-end can easily upset the handling of a car. IIRC my early days on bias tires they would typically lose grip terminally when pushed just over their limit. I've had lots of track and hard street cornering on modern ( radial ) tires which hang in over limit and so allow one to recover from a slide very well.
Steve

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