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cassecou

FZ-07 tire size

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cassecou
I don't know much about tire sizes, so I would need some guidance in that field.
In some bikes I have owned, I have tried to increase the rear tire size. It is often doable, but many have suggested that the only  advantage is only for the "look" only. Increasing the tire size will make the bike harder to corner.
The 07 comes with a somewhat large tire (180). Would it handle better with swapping to 170, or even 160?
 

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rotaryryan24
This is just my opinion, the width and profile of the front tire will effect handling more than the rear. Stay with the 180 in the back.

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nmucat
I love the 180 out back. With my last bike having a 200 and a buddy upgrading his to a 250 (cruiser/choppers) I didnt notice much of a difference, now a 300 ya that thing will not lean.

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howworkclutch
It's more than just leaning. Wider tires are heavier. The suspension isn't setup to handle that extra weight.
 
You want as little "unsprung weight" as possible.
 
When the wheel goes over a bump it's pushed upward with a lot of force. Once all that weight goes into motion the suspension tries to slow the movements of the wheels, stop the movement of the wheels, and then reverse the movement of the wheels. All in a manner that is quick, smooth, and unlikely to upset the rider.
 
Besides having a spring to soften the blow of the roads imperfections, the shock also has an oil dampening system. Without it a bump would cause the suspension to pogo. When you go over a bump the bike responds by boing-boing-boinging. On a series of bumps the suspension could become out of sync with the bumps and, under the right conditions, cause a complete loss of traction and/or toss the rider into the air.
 
The damping system is crucial to proper suspension operation. Mega bucks are spent getting dampening systems tuned to the bike/rider. And suspension should always be your first upgrade.
 
The damping system used a fluid and valves to slow the springs down ant tame the boinging. The valves and fluid are variable. If the fluid is changed then the calving must be changed. If the spring is changed thee fluid or valves must me changed. If the riders weight changes the spring must be changed and therefore the fluid and/ or valves must be changed.
 
Since a heavier tire has more mass it will reach a higher velocity over a bump than a lighter tire. The suspension needs to be changed in order to function properly.
 
On a lard-assed chopper with no rear suspension, a well chosen tire profile can be benificial. Suppose the bike is lowered to the point where cornering means scraping hard parts. If the profile is proper, it will lift the bike a bit when leaned, giving another degree of lean angle. Sadly most chopper builders are idiots and even more chopper jockeys are riding choppers for their ego. Performance of the bike as a whole suffers. I've ridden old school choppers that had no rear suspension and still rode really well, but they employed intelligent design and were very well thought out.
 
A fat heavy tire on a sporty bike can be made to work but it will never perform like a skinny tire with the right profile.
 
Unsprung weight is your enemy.
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howlinhoss
I think the Yamaha engineers nailed it with the 180 rear. No complaints on my end.
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olderthandirt
I have read where many magazine testers said that the 180 on the rear of an FZ 07 is too big....and I believe them. If you corner hard on these bikes...you notice that that last bit of full lean requires a lot of effort. The testers and journalists say the lean gets "heavy" at extreme lean angles. Mine does. I believe that a 170 on the rear would be a huge handling benefit. I may try that next year after I do some rim size research.
 
My opinion...a 180 on this bike is nothing more than a marketing tool....AND so YAMAHA could use the exact same rims that are on the FZ 09 to save money.
 
A 200 size tire on the rear of a FZ 07 is for posers....and will make the bike handle worse. A lot worse.  
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Guru
I never had a bike before with a 180 at the back. I always had smaller. I have to say that I think Yamaha went for looks with such a big tire. Less wide would have been fine too.
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targaflorio
A wider tire will give you a bigger contact patch. That may improve traction for you, especially accelerating hard out of a corner. I would expect a skinnier tire to slide before a fatter tire. A bit more rear wheel braking I would think.

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Greenhound386
A wider tire may give you less usable contact patch depending on the profile of the tire and the rim. Changing to a stickier compound tire will yield far better results for traction than a bigger tire. Hell, even a smaller tire could fare better.
 
I don't think Yamaha was going for aesthetics with the 180. I'm guessing it appeals to riders that want to graduate to a supersport or that simply want a tire with equivalent characteristics to a supersport. I love the fact that I can use my own race take-offs if I want. Otherwise, there is a massive selection of great 180 tires built for different purposes.
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howworkclutch
A wider tire will give you a bigger contact patch. That may improve traction for you, especially accelerating hard out of a corner. I would expect a skinnier tire to slide before a fatter tire. A bit more rear wheel braking I would think.
 
 
It's far more complicated than that. Fat tires should have wider contact patches if you apply common sense. But common sense never stands up in the face of science.
 
A skinny tire can easily out perform a fat tire. I've seen it with my own two eyes. A good friend of mine runs 90's front and rear on a vintage norton. He routinely passes others in corners to prove a point: tire width has nothing to do with grip in 99.999% of cases.
 
You have to factor in tire diameter, suspension behavior, tire pressure, tire compound, and bike geometry.
 
If you don't take the whole system into consideration you'll do yourself a disservice. One that might cost you.
 
I haven't yet made a study of this bikes gripping ability under differing tire pressures but I have found better grip below 30psi front and right at 30psi rear. Since my wreck I don't go hunting for the performance envelope so I'll leave that to someone who has more guts than I.
 
I suspect a 170 or 160 would perform as well or better than the 180. But at what cost?
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turbhoe
A wider tire will give you a bigger contact patch. That may improve traction for you, especially accelerating hard out of a corner. I would expect a skinnier tire to slide before a fatter tire. A bit more rear wheel braking I would think.
It's far more complicated than that. Fat tires should have wider contact patches if you apply common sense. But common sense never stands up in the face of science.
 
A skinny tire can easily out perform a fat tire. I've seen it with my own two eyes. A good friend of mine runs 90's front and rear on a vintage norton. He routinely passes others in corners to prove a point: tire width has nothing to do with grip in 99.999% of cases.
 
You have to factor in tire diameter, suspension behavior, tire pressure, tire compound, and bike geometry.
 
If you don't take the whole system into consideration you'll do yourself a disservice. One that might cost you.
 
I haven't yet made a study of this bikes gripping ability under differing tire pressures but I have found better grip below 30psi front and right at 30psi rear. Since my wreck I don't go hunting for the performance envelope so I'll leave that to someone who has more guts than I.
 
I suspect a 170 or 160 would perform as well or better than the 180. But at what cost?
would an 170/60 be lighter than the 180/55? if so, by how much?

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botticelli
A 160 is the right size for this bike.
 
Yamaha went with the 180 for two reasons looks and to use the same rims as the FZ09 to save cash.
 
The problem is you can put a 160 on it because the rim is too wide. Short of a rim swap, just run the 180. As many have said there are some advantages in that everyone makes a 180 tire so you have choices out the a$$
 
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pattonme
A 160 is the right size for this bike. and to use the same rims as the FZ09 to save cash.

I wish at least the front was the same as the FZ09... The FZ07 is a screwball rotor carrier config. The 160 is the correct tire but you can get the benefits from a 170 except that tire availability is considerably less. There are many race tires in 160 size so even that justification falls flat. No doubt Yamaha marketing thought they were doing their sales numbers a favor by stipulating the 180. Silly rabbits...
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faffi
I'd like a 150/70 on a 4.5 rim. No need to go wider, and the reduced weight along with the narrower profile would aid comfort and make the bike steer quicker AND more accurately.

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DewMan
I have read where many magazine testers said that the 180 on the rear of an FZ 07 is too big....and I believe them. If you corner hard on these bikes...you notice that that last bit of full lean requires a lot of effort. The testers and journalists say the lean gets "heavy" at extreme lean angles. Mine does. I believe that a 170 on the rear would be a huge handling benefit. I may try that next year after I do some rim size research.  
My opinion...a 180 on this bike is nothing more than a marketing tool....AND so YAMAHA could use the exact same rims that are on the FZ 09 to save money.
 
A 200 size tire on the rear of a FZ 07 is for posers....and will make the bike handle worse. A lot worse.  
I'm in no way questioning that you've read it but I'd like to educate myself on this subject and would love to read them as well. If you've got links to or list of which dead tree issues you've read that speak to this subject I'd love to read them. I've not read any reviews that even comment the rear tire size other than a rote mention of the size.  Thanks @olderthandirt :) 

DewMan
 
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gregjet
Faffi, I never thought I would be saying this but I think a 150 would be too small . It think there would be too much deflection and the contact patch would be the wrong shape ( flat oval across the tyre rather than along it , but I stand to be corrected). 160/60 or even 70 maybe would have been optimium I suspect. I would LOVE to ride a properly suspended 07 with a right size rim and a 160 ( maybe a 150/70 to compare as well) on a track to compare with a stock one. As a vERY rough guide, there are plenty of similar power motorcycles, with slightly more weight ( not too many this light), that have had the tyre allocation tested to the max. all over tracks all over the world. Basically 160 and 170 have ended up being the optimium ( ER6/650 ninja, SV650, the class Ducatis, etc), and these have been severely researched for a while.
On an interesting note I raced NSR250's which had about the same HP ( 70) but weighed less ( 128kg) and they were best at 150 and 160.
 
DewMan. If you are quick you may be able to view the official MotoGP site video ( I think it is a free one) on tyre tech that was released in the last couple of weeks. Lots of info on how tyres work , though general. It may surprise you. For example the MotoGP bikes contact patch is quite small on a 165kg bike with 300hp.
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faffi
A 150 could be too narrow, depending on how one rides, I suppose. My son's CB400SF has a 110/70 front on a 3.00 rim and a 140/70 rear on a 4.00 rim and you can clearly feel how much more neutral i rides and also how little it is deflected by mid-corner bumps and dips compared to the MT07 of mine. That may well be down to more than just tyres, of course, but the bigger the difference in width between front and rear tyre, the bigger the difference in the trajectory they must follow. Ideally, front and rear tyre should be the same width, and also of zero width. By theory, of course. Wider tyres do provide slightly more grip and can spread the load over a greater area, reducing wear. They can also carry a greater load. But otherwise, narrower should be better.
 
Moto3 seems to run a 2.50 rim up front and a 3.50 rear, with a 90/580 front and 120/600 rear tyre respectively. AFAIK, they are the fastest cornering GP bikes available at the moment.

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jhonore
Here
 
Your welcome.
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botticelli
A 160 is the right size for this bike. and to use the same rims as the FZ09 to save cash.

I wish at least the front was the same as the FZ09... The FZ07 is a screwball rotor carrier config. The 160 is the correct tire but you can get the benefits from a 170 except that tire availability is considerably less. There are many race tires in 160 size so even that justification falls flat. No doubt Yamaha marketing thought they were doing their sales numbers a favor by stipulating the 180. Silly rabbits...
Just buy an FZ09 front rim and use it on the 07. That is what I did when I wanted an extra set of wheels. And the nice thing is most ppl look to sell the neon wheels.  
 
 

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faffi
Do the wheels interchange directly between the 07 and 09? Front as well as rear? Brake discs also?

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mossrider
Do the wheels interchange directly between the 07 and 09? Front as well as rear? Brake discs also?
Yes. Yes.
Kind of.
 
07 has scalloped discs, 09 has smooth but interchange. Front wheel uses different spacers too due to different axels because of different forks. I have six wheels for my race bike of mixed 07/09 origin. I just bought extra front spacers to adapt 09 wheels to my bike.
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faffi
Thank you very much, mossrider :)

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gregjet
jhonore,
Good find, that video. It says lmost everything we have been saying for ages. Left out carcass stiffness and deflection necessary for the right size contact patch but it's otherwise all there.
 
 
 
Admin: Any chance of a link to that video being stickied somewhere on the forum?
 

Go forth and modify my son...go forth and modify...

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