Raising the old tyre size debate, with apologies

[Angrybird]

Another vote for 190/55. Slowpoke's bang on, it'll shed 20kg off your bike in cornering performance. I'm running a Metzeler Z8 on the rear & getting good mileage on the ZX12 too, fwiw.

It is worth something Madness.. thanks mate. The bike came with a square 190 50 Continental sports tyre almost to the canvas and I thought it cornered quite well :-) I fitted a rear 190 55 Sportsmart last night (a job for the experts in future.. stiff carcass) so I think I am going to have to be careful when I next aim it at a bendy bit.

[Angrybird]

Dunlop say the 180 or 190 are suitable for 5.5 or 6.0 inch rims.

Each tyre makers actual fitted widths vary a bit too - some 180's are exactly that some a few mm narrower the widest I've measured was actually 185. I must get out more .....

http://www.dunlopmotorcycle.com/tire...t/sportmax-q2/

Brilliant AllanB. This was exactly the info I was looking for after someone referred to it in another forum. Car tyre makers always provide it so that you can match your tyres. There are fewer choices on bikes which may explain why this info comes to hand less readily.

[Angrybird]

Mmmmm.... That would explane it... I knew different tyres had different shape, but never realised it was because manufacturers stuffed arround with the profile number.
That would explain why we put a Shinko 100/80 on the front of an FZR250 and it looked like we put a MTB tyre in it.....

Yeah, I know.... shouldn't buy tyres where the manufacturers name starts with S....

I read an article by a big mileage American biker who tried Shinkos on his VF800? He was pleasantly surprised. I met a guy on the Matata straights near Whakatane who fixes bikes and did the Castrol 6 hour back in his day and he was singing the praises of one specific Shinko. Said that a friend who usually swears by Michelin 2 cts "almost" made friends with them. That it was snobbishness that limited his ability to give the cheaper brand a fair go and that half the time the way you believe your tyre will perform is the way it will perform. I agree with him. When I am an expert in an area I know all the shortcuts. I have been off bikes for close to 30 years and so I am no expert. In starting at the very bottom of the heap I am going with only the best written-up tyres and taking note of every last little comment here for what I might learn from it.

[Angrybird]

Bad news, your math is correct, but the designation no longer means exactly as you have said. Manufacturers use that as a guide and then make the tyre whatever size they want really. There are many many tyres on the Market of varying sizes, all using the same carcas.

The exact dimension of any tyre is relative to rim fitment. All you can be sure of, is that a 55 profile of any given tyre, is taller than the 50 profile in that same model.

Back in the day you could get a black or a blue one. Nowadays if you buy gourmet organic produce overseas for example it will give you every last piece of info about the producer including his shoe size. People want to know and there is a competitive edge to be gained from supplying this info. Makes me think we are still in the dark ages in terms of how manufacturers specify their tyres.

[Angrybird]

Okay, I will correct you....

The /55 and /50 refer to the PERCENTAGE of the width.
So it is 55% and 50% of 190 respectivly.
Thus 104.5mm and 90mm respectivly.

So OP had it right, 14.5mm difference in side wall height.

50% of 190 is 95 That is where I went crook in the first place.

[Angrybird]

Thanks to you experts I went for the 190 55s in Dunlop Sportsmarts. This tyre looks nothing like the 190 50 Pilot Power 2CT on my Fireblade. I have taken a rough measurement just to make sure that what I am seeing isn't imagined but the 55 Sportsmart appears way skinnier than the 50 2CT.

Side by side the Michelin looks like the Michelin man ie a big fat drag slick in comparison. In fact if there is a different in width it is not great. The 190 55 just has a more chiselled look to it. No doubt because this tyre is designed to contact the road when it is lying on it's side.

Something else I have noticed is that the Honda seems very reluctant to go into a low speed turn such as going around a roundabout in the city. The Kawasaki even with a bald old Conti Road Attack seemed more responsive and so I thought it must be because the seating position is more upright and I am putting less weight on the higher handle bars.

Actually low speed turning is a bit of a drama for me after a long period of absence from bikes and so it is something I practise at the end of our cul de sac. When I circle it on the Honda I just about use the whole road.. imagine that as a 20 cent piece. When I do "roundy-roundies" on the 14 it is as if I am only requiring 10 cents worth.

On the 190 50s chicken strips are a way of life. After riding the ZX around in ever decreasing circles I was somewhat bemused to see I had nearly used the whole tyre yet it felt as natural at that lean angle as the 190 50 shod Honda did nearly "upright."

Just by way of first impressions I am forced to conclude that the 190 55 is a tyre which is designed to go around corners.. the 190 50 for US freeways. In fact I am now convinced that my sense of the Fireblade's 190 50 fighting you is real.. it simply doesn't like being on it's side. 190 55 cf 190 50 doesn't sound like much but in reality the difference is chalk and cheese.

As for the way it affects gearing I did a quick calculation and from memory it is 3% higher. When in first gear the engine now seems more "raspy" in certain rev ranges. I wonder if it just spun through there without my noticing when the gearing was standard. Something I can live with for the moment but when bucks permit I will probably add a tooth to the rear.

[Dave-]

Something else I have noticed is that the Honda seems very reluctant to go into a low speed turn such as going around a roundabout in the city. The Kawasaki even with a bald old Conti Road Attack seemed more responsive and so I thought it must be because the seating position is more upright and I am putting less weight on the higher handle bars.

Actually low speed turning is a bit of a drama for me after a long period of absence from bikes and so it is something I practise at the end of our cul de sac. When I circle it on the Honda I just about use the whole road.. imagine that as a 20 cent piece. When I do "roundy-roundies" on the 14 it is as if I am only requiring 10 cents worth.

checked suspension?

if not, have a read of this thread:
http://www.r6-forum.com/forums/showthread.php?t=80410

Yes it's for an r6 but the process is the same, I'll assume your fireblade has fully adjustable suspension....if not do what you can and see how it goes.

also check tyre pressures too!