Scorpion tyre speed rating

[oythaammaowaere]

Hi all
I have just bought a '95 Skorpion sport which desperatley needs tyres.
Ive never had to buy a new modern bike tyre...previous bikes old brits,and for my sins a harley!
My question is why are all the recommended tyres Z rated?
Is this due to the tyres adhesion properties rather than speed rating?
Would it be pratical and safe to use say an H rated tyre?
Thanks
Ian

[Skorpion]

If I remember rightly, the original tyres fitted to the Skorpions were H speed rated, but most owners now fit ZR which is a little overboard but more common.

[Bill Jurgenson]

nope,
at the time (1993) there was nothing but ZR rated tires available as radials.
There is no other reason. HR rating is more than sufficient.
There is no reason at all for anything "faster."
The best tire for the bike is the Bridgestone BT090 in 110/70 front and 140/70 rear.
the 4" rear wheel is too narrow for the 150/60 in the registration but, like the HR rating thus was due to there being nothing smaller as a radoal at that time.
this not my whim; the tire manufacturers give a reference rim size for a given tire, all of which are wider than the 4".

[oythaammaowaere]

Thanks guys that helped a lot

[Mike G]

I have had very good results in handling and wear with Michelin PR2 110/60 front 150/70 rear (dual compound). The rear is techincally 'too big' and lifts the back and raises the gearing slightly but doesn't foul chain or guards. The pair have done 14,000 km so far and from the amount of tread left will easily reach 20,000 km.

Mike

[MarkM]

My '01 came with a front Power 2CT at 120/60, and a rear Pilot Road2 at 160/60. They are pinched, and I have other bikes that can use that front, so I am tempted to replace them with the 110/70 & 150/70 set of Road2 like you have. There are only a few hundred miles on these now.

We should compare pictures about how pinched these tires are, and I'd like to see pictures of the Bridgestone BT090 110/70 front and 140/70 rear that Bill Jurgenson suggests.

I commute on my bikes, and am generally pleased with the Pilot Powers and Road2's that I've used.

Cheers,

Mark

[Bill Jurgenson]

Despite having worn out a few set of BT 45s, I can't seem to find a picture of the Skorpion with them, at least not one where you could see the tires.
Here is that same bike with a BT090 in 140/70 on the same rim:

140/70 on 4" Brembo wheel

and this is what the contour of a 160 should be:

165/55 Bridgestone on a 5" Marvic mag wheel (my racer)

I mounted a 160/50 once - once to often - on my Tour way back when I didn't know better:

Here as you can see with the shitty Grimeca wheels (must be about 7-8 years ago) and you ca see how rediculously pinched that Bridgestone is. No fun to ride, either and it forced me to add a steering damper to help against the excessive kickback. By comparison my racer never need a damper at all.
Skprions don't need dampers if the tires are right.
I can only keep repeating, that 150 tire are already too big for a 4" rim; a bad joke! That is not my opinion, that is what the tire makers say and they are right.
Stick a 140/70 BT45 on the bike! Save money and stress and increase your own safety.

[Old Dog]

Bill,
will those 130/70-17 Heidenau K66s fit on the Gremica 4"?

TIA

[Bill Jurgenson]

yup,

remember, the first Skorpion Tour, 1994, had a 130 rear tire and a 43t chainwheel.
The Sport had the 150 with 39t wheel.
in terms of final drive, i.e. rolled out cirumference/revolution, both are the same.
as everyone will have found out by now, I used the 43 with the 150 and later with the 140 rear tire on the 4' rim and also with the 130 on the 3.5" rim.
right now, I am running a 41 with the 130 and 3.5" rim but I do have a shorter 5th gear.
Of course the slightly larger diameter of the 140/70 makes the final ratio a bit longer than it would be with the 150/60.