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Discussion Starter #1
I just bought a 120/70 for the front. I would rather have bought the stock 120/65 but had the choice of a 120/60 or 120/70. The guy at the shop said the 70 would turn quicker. Two questions: 1. Will it turn faster and 2. Do I have to adjust the fork tube height?
 

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You can tell when a salesman is lying when his lips move. The 70 series tire is taller raising the front. Raising the front makes the bike turn in slower. The 70 series tire ought to be about 6mm taller than the 65 so you can raise the fork tubes in the tripples that much to compensate. Raising the fort tubes lowers the front.

I think many people run the 70 series without doing anything to the bike.
 

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Tire size designations include:
  • Section width in millimeters
  • Aspect ratio (section height divided by section width) as a percentage
  • Rim diameter in inches.
The stock front tire on the 2000 to 2002 ZX-6R has a size of 120/65 17, which indicates that it has a section width of 120 mm, a section height at 65% of the section width or 78 mm, and a rim diameter of 17 inches. A 120/70 17 tire shares the section width and rim diameter of the stock tire, but has a section height at 70% of the section width or 84 mm.

The section height of a 120/70 tire is 6 mm greater than the section height of a 120/65 tire. As a result, a 120/70 tire stands 12 mm taller than a 120/65 tire.

The taller 120/70 tire effectively increases the rake, which slows steering and increases straight-line stability. You may like this just fine.

To maintain the stock ride height, raise the forks 6 mm or 1/4 inch through the triple clamps.
 

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Discussion Starter #4
Thanks for the explanation. Quicker turn in my ass. I found out what a difference there is while taking a long sweeper at a decent speed. Caught me off guard alittle. I'm going to raise the forks up 6mm and see how that feels.
 

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Errr, if you like the corners, the 70 is the way to go. Once your rake is set back, the 70series gives more contact patch at full lean than the 65. Thus most race tires are only avalaible in 70 series.

98 6R. TBR slip-on. No poser add-ons..
Memeber 51
 

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Discussion Starter #6
Okay, so once i raise the forks up 6mm I should be able to turn quicker and have a larger contact patch?
 

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Assuming identical compound and construction, a 120/65 tire has a stiffer sidewall than a 120/70 tire because of its shorter section height. A stiff sidewall deflects less, aiding steering but offering a smaller contact patch at lean and inferior bump absorption.

Even with identical ride heights, the 120/65 tire provides quicker steering and better feel. The 120/70 tire provides better bump absorption, a larger contact patch, and ultimately more grip. The choice is personal.
 

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Raising your forks will allow you to turn quicker and easier, but if you do not have a steering damper on your bike, you will get a front end shake at higher speeds
 

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I got a front tire blow out on an off ramp at about 45mph. The good news is I managed to keep it up. When I went to get a replacement tire I was told the same thing. That the 70 "will turn faster than the 65" so I bought the 70. The only reason and I mean only reason I bought the 70 was it was all they had in stock and I was supposed to go on a big ride that weekend. My point is I have had the 70 on and never changed any geometry on my bike and it still feels fine. at first the front tire will feel loose but only because you are paying attention to the the front end because of the new tire.


01 YELLOW
 

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Discussion Starter #11
Dave6r, you hit it on the head. Went out riding some twisties yesterday and the front end was shaking pretty bad, especially when coming out of the turns. I ordered a damper so I'm going to keep the speeds down until I get it.
 

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So what sort of characteristics, apart from quick steering, will the 120/60 fronts deliver, good and bad. Would fork adjustments also need to be made?
 

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Putting a 60 profile tire on the front instead of the 65 would lower the front about 6 mm. There is no way to compenstate for it because the forks are already to the top of the clipon. Lowering the front that much shouldn't cause any problem with instability. Supposedly the 60 profile gives a smaller contact patch but on the street I don't think you will notice the difference.
 

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thanks swjohnsey. The info is much appreciated.

I should introduce myself. Aussie from Sydney NSW, owned a 2nd hand ZX6R for a year and a half now. A great all-rounder. Outscratched on the track by gixers and r6's, but the trade-off is comfort and and good pick up from around 4-5000rpm. I've done 14,000km (8,750 mi for those still using imperial measurements). Just recently had its 24,000km service. Didn't do to badly $$$ wise. Needed 4 exhaust shims replaced however, a cam chain tensioner which was covered under warranty, and new set of front pads. Will be putting on new set of rubber this week and will probably stick with the standard 120/65 front.
 

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quote:
So what sort of characteristics, apart from quick steering, will the 120/60 fronts deliver, good and bad. Would fork adjustments also need to be made?
A 120/60 tire gives quicker steering and better feel than a 120/65 tire at the cost of inferior bump absorption, straight-line stability, and grip at lean.

If the top end of the inner tube is flush with the upper surface of the handlebar holder, you cannot increase the ride height at the forks.
 

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Rob, you took all the words right out of my mouth this forum... argh...
shoulda got on earlier.

Keep this in mind guys... Kawasaki can spec any tire they figure will aid performance when engineering a bike, and for this bike they picked a 60-series tire... think about it.

As in most things in life, there's always trade-offs to balance. But if a 60-series tire could offer a better compromise between cornering agility and overall stability, Kawi would have no doubt made it standard issue. You'll go a LOT farther asking about and checking into different tire brands and models than actual sizing. You can improve performance A LOT by picking a tire that suits your riding style, and damn there's a lot of different choices out there...

Good luck.
 
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