70/16 tires ?

[ribbert]

No problems whatsoever to mix different front and rear tires.

....... Not sure about a radial on the front and cross ply on the rear though, that could be another kettle of fish.

Before changing to a 17" rear I ran many combinations of radial front and bias rear. No problem except for just one combination. It was so bad I pulled up a number of times on the way home from the tyre fitters, firstly convinced they had forgotten to tighten the back wheel (it was that bad) and then to check for some major issue with the frame.

After gingerly riding home and thoroughly checking the bike over several times I could only conclude the tyres didn't like each other. I sort of learnt to ride around the problem once I new what to expect and what would set it off and in what direction it would lurch but changed the tyres over well before they were due and everything was good again.

I can't remember what the tyre combo was but it had never happened before and never happened after, so, as a rule I would say no problem.

I did many tens of thousands of km's on mixed tyres - track days, trips, high speed, rain, mountains, no problem.

Noel

[Vilike]

Okay, thanks for all your answers.

I purchased a pair of a Sport Demons of a /70 size. 

Pirelli website about the new Sport Demon :

" Uniform and progressive performance in all riding conditions thanks to the rear multi-radius profile.
    High grip on wet and dry surfaces with excellent mileage.
    A safe and reliable tyre in all riding situations, with a particularly favourable cost/quality ratio suitable for Sport
    Touring Motorcycles."

[4everFJ]

Why do you want them in /70 profile?

As I can see, the load and speed index for their /70 profiles are waaaay to low for the FJ.

The front Sport Demon 120/70 - 16 M/C 57P is only rated up to 230 kg / 150 km/h.. and the rear 150/70 - 16 M/C 68S only up to 315 kg / 180 km/h..

If those are the ones you have bought, they are not to be used on an FJ!