changing tyre sizes advice/help

[clancy]

currently my nc35 has 120/70/17 and 150/70/17.
putting new tyres on it soon and was wondering if i was to change them to 120/60 and 150/60 will this cause me any issues?

cheers, leigh
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KLX 300r

[stinkwheel]

It's a lower profile. It'll lower the front by 6mm and the rear by 7.5mm.

That'll MARGINALLY increase the rake angle but by so little I doubt you'd notice

You'll tend to run more onto the side part of the tyres at a lower lean angle but with a slightly larger contact patch.

This means, if you're using the full width of the tyre normally, you won't be able to lean as far before running off the edge but should have a little more grip on the way there.

If your speedo runs off the front wheel, it'll overread slightly (not by much, 2.4% taking it by raw maths but pressures, wear etc. make this calculation meaningless).

So, by the numbers it won't make a massive difference. The bike will probably feel a bit more "grippy" and stable and need slightly more pressure on the bars to make it change direction.

You can't really put a figure on how that will feel when you ride it and if you'll like it though, the only way to see would be to try. I doubt it'll suddenly turn into an unrideable monster though.

I changed the front tyre on my VFR750 from a 70 to a 60 section and left the rear as it was. This made more of a difference because it lowered the front by 6mm but left the back where it was. The increased contact patch size and lower profile was overridden by the decreasing of the rake angle. So I got a bike that felt both grippier and quicker to steer.

I decided on this course of action because of the huge disparity between the amount of tread on the front tyre I was using compared to the rear.

So this was the wear pattern with the 70 section front:
https://i48.photobucket.com/albums/f216/stinkwheel/70sec.jpg

And this is with the 60 section front:
https://i48.photobucket.com/albums/f216/stinkwheel/60sec.jpg

As you can see. It 's closer to the edge of the tyre for the same angle of lean on the lower profile tyre. Fine in my case because I'm still going to run off the rear tyre first.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[clancy]

ah ok thanks for the help, the only reason i ask is i will need new tyres soon and the ones i want only come in a 60 section rather than a 70. so essentially im going to go closer to the edge of the tyre on the same lean angle ?

cheers
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KLX 300r