New tyre but back end feels strange

[rickyt28]

Just put a Pirelli Diablo on the back after getting a puncture in my Avon Viper Sport last week. Did 95miles on it yesterday to scrub it in.
The Pirelli is a lot more rounder so the bike feels a lot easier to flick from side to side, but i have noticed that when going in a straight line, if i twist my body from side to side (rather than weave), the rear end seems to drift easily like it is flexing a lot on the tyre. I put this down to maybe the pressure needing a bit of a top up as it also felt a bit soft to the touch but i checked the pressure and it was 38psi and the tyre says 42psi max cold. Do you reckon i should just inflate it to 42? Or is this a normal feeling i am experiencing? I just didnt notice it with the Avon.

[cargo]

????????????????

My first thought .....................is the wheel put back in properly ?

A more rounded profile front tends to slow the steering......................I'm not entirely sure that a more rounded rear will quicken the steering.

I run pirellies super corsa pros or whatever they are called now at 30psi rear and 31psi front ?????

[rickyt28]

At first i thought i hadnt put it back on properly, but i stopped, had a good look, gave the wheel a good yank and it is solid. I put the wheel back on exactly as it came off, lined up with the swingarm markings exactly as it was before. And with all the spacers, i even had to ease the swingarm open slightly to get the wheel to go in properly. Theres no wobble in the back brake either so ime prety positive the wheel is where it should be.
Its basically that feeling of when you wiggle the bars from side to side while your in a straight line n the back end feels like its sort of wiggling in the opposite direction (a bit like a tank slapper i think, but not so aggressive). I cant tell whether its a normal thing, or whether there is some play somewhere, whether its the wheel, tyre, or maybe the suspension.
I can only really feel it if i sort of make it do it if you know what i mean, but i had noticed it when straightening up out of turns ever so slightly

[cargo]

Could be a mismatch in your tyres whats on the front ? ?

I normally like to changes tyres as a pair

[jake]

get it up on your paddock stand and spin it. eye it from the side from a fixed point, and then again from the rear.
doubtfull, but could be a toad out of shape tyre

[rickyt28]

Front tyre is a pirelli dragon, rear a pirelli diablo.

As for the paddock stand... i dont actually have one yet, i had to remove and refit the wheel Pikey style lol using a mate to lean the bike over on the stand while i whipped the wheel off, propped the swingarm with timber and then used a mate again to lean her over while i got the wheel back on. hehe

But i have had the wheel off the floor and spun it and i havnt seen anything untoward. I will get it on a stand asap n have a proper look. I'm waiting for my neighbour to get me a paddock stand, he reckons he can get me one for free, he marshalls at Oulton park and says he knows a guy he myt b able to get me one from.

[rickyt28]

It could just be me being paranoid though you know, I've only had the bike 3 weeks so i might just have not noticed what the back end felt like before. I only really paid proper attention to the back tyre on sunday because i'd put a new tyre on

this is the exact tyre:
DIABLO 160/60 R17 TL 69H M/C
manufacturers
part number (sku): 1565200
Speed Index: H: These tyres are approved for speeds of up to up to 130 mph/210 km/h

Features: impressive handling and response thanks to the enhanced profile.
- Mileage and regular wear thanks to the Diablo like pattern design.
- Exceptional wet and dry grip thanks to the moto derived compound.