I know that there are people that do, but I would not run a radial on the rear. Bias tires can handle the lateral stress that is put on these big bike's rear tires better than radials can, IMO.

 

There are a couple of motorcycle models ('08 H.D. Rocker, '09 C.V.O. Softail Springer, '15 FXSB Breakout, for example) that mix the front & rear, according to their specifications.
There must be disagreement by some manufacturers on this issue, but there are examples of mixing. Usually, the rear is the radial, while the front is bias.
I did that configuration on my '15 Vulcan Voyager 1700 for awhile, and they seemed to work out okay. Traded off the bike, so I don't know how well they did, long-term.

 

I've been running a radial rear and bias front for quite some time.I also did the infamous dark side for years (radial car tire out back and bias front) both with no problems

I used to run cars with radials up front and bias out back for decades without incident

 

What do you like about that setup? Does the radial make the rear feel more planted? What air pressures do you run?
What tires are you using?

Thanks for sharing your experience! I really like riding curvy mountain roads here where I live in Virginia, can’t imagine how that would feel on a car tire!

 

The Motorcycle Tire Question: Radial, Bias or Both? (rideapart.com)

 

From Wikipedia: "Bias and radial tires have significantly different dynamic properties. They deflect differently, create different cornering forces, have different damping characteristics, as well as other differences… "

That's kind of funny since front and rear wheels 'deflect differently, create different cornering forces, have different damping characteristics, as well as other differences', so wouldn't mixing tire types make those 'differences', different?

 

I am an old school racer that occasionally ran radial/bias. We wanted the best tire for our bike, style, and track, and often they were not the same brand. No I run on the dark side, so front/rear has mostly been a non issue for me. Motorcycles, unlike cars, require a stiff sidewall, so MC tires in either construction will work.

 

So I just got a text from my buddy who used to race for Team Honda Redwing back in the 80’s…
He said,…

“I’m running dual sport tires on my Harley (Street Bob) now. I have a radial on the rear and a bias ply on the front. As far as the 1000 interceptor goes, I rode one of those back in the day, and while it was super fast, it was very top-heavy. It did not handle as well as my 750 interceptor but was crazy fast in a straight line. Freddy Spencer was my hero. He could go fast on any Honda. Radials, at least on the rear makes total sense. We drive our bikes using our rear tire in high-performance situations. It could be interesting to have a radial on the front and have a high leaning angle breaking episode, and the tire starts squirming. (Haven’t experienced) squirming, but I’ve definitely experienced pushing. It’s a bad feeling up into the moment it finally hooks up.”

My buddy’s nickname is ‘Crash’, the guys on his team gave it to him (he earned it). We used to race mountain bikes together back in the days after his professional career.

 

Racers don't race 900 lb motorcycles (at least most don't), don't weigh 275+ lbs like many of us do, and generally don't ride 2 up when racing, so they don't have to deal with the lateral forces on radial rear tires that big bikes with heavy "cargo" do. Arguing that radials (motorcycle tires, not car tires) on the rear of big bikes is OK because racers use them is like comparing apples and oranges.

A radial car tire on the rear would not be an issue (at least with respect to lateral forces), as car tires are designed to handle much higher loads that motorcycle tires, so that is another apples and oranges comparison.

 

Racers don't race 900 lb motorcycles (at least most don't), don't weigh 275+ lbs like many of us do, and generally don't ride 2 up when racing, so they don't have to deal with the lateral forces on radial rear tires that big bikes with heavy "cargo" do.

Given the speed and the tightness of the turns, I'm guessing race bikes put a lot more lateral force on their tires than any street bike, regardless of the load.

 

The Dunlop Goldwing rear tire D250 is a radial as is the Bridgestone Exedra G853/G852. But other cruiser/touring tires are bias. When you could still buy car tires in either bias or radials, radials have noticeable squishy sidewalls and often looked like they were low on air. Not today, not sure why. But all MCs need stiff sidewalls. Sport bikes get away with radials because their sidewalls are like 3/8". But touring radials have such stiff sidewalls, I doubt the you could tell the difference between radial/bias on un mounted tires even by sitting on them. I think that

 

Having run both bias front and rear,and bias front/radial rear on the Vulcan and my previous bike,1984 Honda V65 Sabre,about the same weight as a Harley Sportster,I can't tell any difference.

I also went darkside on the Vulcan for a while,and I was surprised to find it actually handled better and easier that way (car radial rear/mc bias front)

 

We've had two Yamaha VStar 1300's. Still have one. Both came from the factory with a bias tire on the front and a radial tire on the back.

 

I just found two more pennies in my pockets....imagine that.
I think we need to remember that the manufacturer's ENGINEERS decide what tire to put on the motorcycle they designed.
Aside from that I'll let Michelin say the rest: Radial or Biased

 

Actually, the engineers do have input, BUT the ACCOUNTANTS make the final decision. Been there done that.
Comes down to compromise.

 

The attorneys have right of first refusal. I never worked with any engineers that would knowingly design or endorse an “unsafe” product. Besides, product testing (more engineers) get between the original design and the finished ready-for-market product. By the way, never worked with any accountants or anyone else who valued their jobs who had the attitude you mention. Curious what your beef with Shinko is all about.

 

My experience in corporate America: Marketing always has the last word unless the legal department really puts up a fuss. The designers (engineers, chemists, whatever) may not even be consulted on the final changes. Original specs go out the window if marketing is determined to have their way. Been there, done that, got in some "I told you so" to marketing when they tried to blame us (in my case the R&D division of a chemical company) for the issues and law suits. I learned very quickly to document everything for my own protection.