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post #1 of 11 (permalink) Old 11-24-2003, 11:05 PM Thread Starter
 
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advice on tyres needed.

Hi, okay, this may be a dumbass question but i'd like to know the answer :)
ive got to get new tires for my baby 92' zxr400-l2, so im now wondering can i use tyres bigger than by default (160/60ZR17) or maybe i can put tyre of size 180/55ZR17 on?
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post #2 of 11 (permalink) Old 11-24-2003, 11:58 PM
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i wider, shorter tire will make your turn in slower...
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post #3 of 11 (permalink) Old 11-25-2003, 12:09 AM
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Re: advice on tyres needed.

Quote:
Originally posted by brozah
Hi, okay, this may be a dumbass question but i'd like to know the answer
ive got to get new tires for my baby 92' zxr400-l2, so im now wondering can i use tyres bigger than by default (160/60ZR17) or maybe i can put tyre of size 180/55ZR17 on?
Depending on the width of the wheel, you can USUALLY go up a size, which I would guess is 170, for you.

If you put a 180 on it, you'll mushroom the tire and cause lots of flex. It could cause weird heating and handling issues. Hard to say. I've never ridden a ZXR400.

But general rule, you can USUALLY go up a size.
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post #4 of 11 (permalink) Old 11-25-2003, 12:41 AM Thread Starter
 
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thanks for the reply's
hmm, still not sure if i should/shouldn't get the 180/55ZR17.
what's about the weird heating?
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post #5 of 11 (permalink) Old 11-25-2003, 12:48 AM
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Quote:
Originally posted by brozah
thanks for the reply's
hmm, still not sure if i should/shouldn't get the 180/55ZR17.
what's about the weird heating?
Depending on what air pressures you use on your tyres. I've heard of (from people I know) tyres blowing (on the street) due to over-pressure.

Just FYI - if you ask any racer, they'll tell you they run anywhere from 29-31psi (you'll have to do your own metric conversions). Max pressures are usually somewhere around 36-42psi, depending on tyres and bike.

At the track, starting cold at 31psi, after a 20 minute session, I measured a 6psi increase in tire pressure.

The short of the long is, more flex generates more heat, more heat means more pressure. More pressure COULD mean BOOM, depending on where you are as far as pressure is concerned. Not trying to scare you. You asked.

Bottom line, I would stick with a 160, unless you're having a hard time finding your CHOICE tyre in a 160.
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post #6 of 11 (permalink) Old 11-25-2003, 01:25 AM Thread Starter
 
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hmm, currently when cold air pressure is about 30psi front and 33psi rear.
the whole idea about getting a 180 is that a friend of mine is selling a new pair for a beer or two so i was just wondering :)
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post #7 of 11 (permalink) Old 11-25-2003, 02:02 AM
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Beer must be expensive where you are.

Well, if it's gonna cost you a couple beers, go for it. I wouldn't use them (at least the rear) on your bike, however.

Front pressure SHOULD be slightly higher in pressure than the rear. All the control is in the front.

I run 30-31psi (front) and 29-30psi (rear) when I'm on the track, wearing Dunlop D207 GP Stars (or similar). By the time they are warmed up, I've got a comfortable 37-36psi in my tires.

Depending on my mood, I usually run 32-35 (front and rear) on the street, sportin' similar tires. I don't get 6psi on the street like on the track, but I still end up somewhere around 37-38psi by the time they are warmed up.
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post #8 of 11 (permalink) Old 11-25-2003, 02:21 AM Thread Starter
 
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hmm, and now im confused, should i use them when i get them? :)
My friends bike was stolen recently so he had no use for the tyres no more - they were meant for the next season(*$&[email protected]%^ thieves!!!).
Well i'd like to get them myself but You (DaDuck748) scared me :) Why wouldn't You use them on zxr400? About handling - i suppose it could get a bit weird cuz the tyre's wider. Dunno what else ;(

Last edited by brozah; 11-25-2003 at 02:28 AM.
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post #9 of 11 (permalink) Old 11-25-2003, 02:34 AM
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There is a REALLY good thread on this, some time ago. I don't remember who posted, but they said something like, "imagine one of your model motorcycles (everyone has at least one of those). lean it, like you would as you're riding it. Then put downward pressure on it, just as you were riding it. You will see how the tire (profile) deforms."

I thought this was an AWESOME demonstration of tire flex.

So, let me clearify... assuming your 400 takes a 120 (front, also assuming your friend has a 120 front), I would use the front, and set the rear aside. The control is in the front, not the rear. If you've got super sticky tires in front, this means you have that much more control in the front.

I hope that cleared (clear as mud?) it up for you.
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post #10 of 11 (permalink) Old 11-25-2003, 02:53 AM Thread Starter
 
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thanks for the input ;)
im off to shop for a beer :))
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