Don't do this

[Omnivore]

So a while back I changed tires to Q'2's. Great tire, super grip, horrible life span. You want to play you have to pay.

The problem, (sort of) was that I put a 120/60ZR-17 on the front and 160/60ZR-17 on the back. Rides great, leans great, fantastic in turns for a few reasons which I won't go into, BUT all the sudden long trips were hurting my posterior and my passengers are always sliding into me, putting a lot of weight on my arms. What the heck this never happened before if anything they complained about almost sliding off the back....

I was looking at the bike and noticed the rear seat was tilted way down towards the front, which I though was a bit odd I had not messed with the suspension. I couldnt sit on the rear without sliding forward... Looked at pics of other Kats they are ever so slightly tilted but nothing like mine hmmm

I looked at the bottom of the fairing and it too was tilted low towards the front quite a bit. I was just about to rebuild my seat to build up the rear to hold the passenger in place and it hit me. The 120/60ZR-17 must be an inch ot two lower profile than the 120/70ZR-17 thus turning my back seat into a slide, but the Q'2 160/60ZR-17 must not be lower profile than the 150/70 it comes with.

So just a heads up if anyone does think about doing this. My tires are about shot so I'll just stick 120/70ZR-17 back up front again, and the problem should fix itself. (Going to try PR3's this time)

[KAT TOY]

I had a set of PR3s and didn't like them. I didn't get better grip or wear than my Conti Motions for a lot less. hope you have better luck.

[Omnivore]

I had a set of PR3s and didn't like them. I didn't get better grip or wear than my Conti Motions for a lot less. hope you have better luck.

Interesting. This is only the 2nd negative thing I've heard about PR3's (the 1st one was self inflicted I think)

So not good grip and they didnt last long for you? Grip in rain? Warm weather? Cold? all of the above? I'm just curious.

I never "land" on anything before I buy it. I bought the Q's on a whim (great tire btw, but in general I really dislike Dunlops)

[rexazz2]

I get a little sloppy with posture sometimes
Keeping your knees tucked in against the tank will make a big difference on your wrists etc

[scottynoface]

The Q2 is a real sport tire, it has a different (taller) profile than a sport/touring tire.

[Omnivore]

I get a little sloppy with posture sometimes
Keeping your knees tucked in against the tank will make a big difference on your wrists etc

Its not that, its the body behind me putting all their weight on me becasue they are sliding forward from the seat angle. Aside from that I think the "new" tilt of the seat puts my weight more forward almost on my upper legs instead of my butt.

I measured my seat at a 15 degree forward angle

[Omnivore]

After some googlin, I figured the front end was lowered an inch by the tire change I made, which is what made my seat slant.

In general the 160-60 is a half inch taller than the 150-70 and the 120-60 is a half inch shorter than the 120-70

[teddy]

the 120/60 is shorter, and generally that size of tire doesn't carry the load rating required for the kat's heavy front end, either...something to keep in mind next time around...

[05RedKat600]

After some googlin, I figured the front end was lowered an inch by the tire change I made, which is what made my seat slant.

In general the 160-60 is a half inch taller than the 150-70 and the 120-60 is a half inch shorter than the 120-70

Erm, your math is off. Remember you're talking circles, which means radius, which means half the diameter. So you're 1/2" off.

[Omnivore]

Na I was going by height, Rim to outside rubber, and q2's specs then the roadsmart specs.

[Kreylyn]

120*.7 = 84mm
120*.6 = 72mm

84-72= 12mm. 12mm converted = 0.4724"

So going on the front from 120/70 to a 120/60 = just shy of 1/2" drop in height. But...

160*.7 = 112mm
160*.6 = 96mm
150*.7 = 105mm

112-96 = 16mm. 16mm converted = 0.6299"
105-96 = 9mm. 9mm converted = 0.3543" (difference just shy of 3/8")

Going to a 160/60 from a 150/70 also is a drop in height... slightly under 3/8".

16-9mm = 7mm total, or converted = 0.2756"... just a hair under 9/32" difference in heights from the front to rear for the angle of the bike.

Avg wheelbase of 1,470 mm (57.9 in) and your looking at a 9/32" drop... That means your angle is decreased on the front by overall .27 degrees.

So your not really looking at a huge difference in angle after all. The bike is lower overall yes... but the difference between front and rear lower isn't that much. Also, the difference is so slight that you could easily adjust the forks in the triples to counter that.

Each measurement discussed is the side wall height, not the diameter so it directly corresponds to the height of the bike.

Now... the effect of having a smaller sidewall = much "rougher" ride. You get alot more vibration and small bumps from the road as feedback into the bike. This means you go from a smooth rider to a much rougher one. Rougher rides simply beat you up. So while it may feel more responsive, it's definately worse for the wear on your body.

Krey