Triumphrat

narrowminded

I'm ignorant on the sizing of tires. I have the opportunity to purchase a set at a good price but the size of the front tire is different from the recommended size in my manual.

Front:120/70ZR17
Rear :170/60 ZR17

The ones I'm looking at are.
Front 120/60 ZR17
Rear :170/60 ZR17

Can someone clear this up for me?
Will the 120/60 work?

Thanks

__________________
"The Glory of God is man fully alive."

steve.g

Yes it will work,but the profile is lower and this will alter steering geometry.Tire sizes work like this...

First number is width,measured in millimeters.

Second number is aspect ratio.This is the profile size expressed as a percentage of the width. So a 120/60 means the profile is 60% of 120mm or 72mm. A 120/70 is 84mm.

Third number is wheel size in inches.

The letters indicate speed rating and if the tire is radial.
Hope this makes sense for you!

narrowminded

Thanks.

__________________
"The Glory of God is man fully alive."

TxGr8WHite

I am currently running a 120/70/R17 in front and a 200/50/R17 in the back.

__________________
1995 900 Sprint Nightshade
1996 1200 Trophy Merlot

narrowminded

Let me see if I've got this right.
The 170/60 has a lower side-view profile, they are "thinner". If I'm thinking right does that mean they are somewhat flatter? If so how would the difference in the front to rear aspect effect leaning into turns if the curvature of the tires isn't the same?
Or am I over thinking all of this?

There are new Dunlop 220's for sale on that auction site for $160 shipped, add $25 for mounting, $215 for tires is pretty good.

Thanks again.
Carry on!

__________________
"The Glory of God is man fully alive."

millwallfcuk

i've always used a 10 55 on my 1200 trophy....

works fine but not sure i'd want to change the front

TxGr8WHite

What is important is the tire overall height, which effects the circumferance. If you were to go with a 60 series tire in the front, your speedometer will be way off, since it is based on the 120/70 front. The aspect ratio differences between the front and back will not make that big of a difference (they are already a "70" in front and a "60" in back. The aspect ratio is used to get the circumferences of both tires close to one another (that is why I had to go to a "50" series in back with the wider 200 tire).

__________________
1995 900 Sprint Nightshade
1996 1200 Trophy Merlot

steve.g

Your over thinking this. Aspect ratio is just the tire companies using a fancy phrase to measure the height (profile) of a tire.
Profile is measured from the bead of the tire to where the tread starts,looking from the side.
Just remember that if you put a lower profile tire on the front,the overall height of the bike will drop a little. Therefore altering rake/trail slightly.
The speedometer will be a little off as well (faster) because now the tire turns more times to cover the same distance.
As to your original question, will a 120/60 work in place of a 120/70?
I would say yes, but your bike will turn a little quicker and maybe feel a little nervous at high speed.
If it were me and I could get a good deal on the tire,I'd mount it up and go for a ride.The worst thing is that you don't like the way it feels.. Good luck!