I bought some race take-offs for my '96 F3 (my track bike). The stock size was 120/60/17 but the new tire is 120/70/17. What effects will this cause? Will I need to setup my suspension differently?

Here's the numbers.

Tire Size Comparison
Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
120/60-17 2.8in 11.3in 22.7in 71.2in 890 0.0%
120/70-17 3.3in 11.8in 23.6in 74.2in 854 4.2%

 

I wouldn't think that would affect anything, because its not that much of a change.ButI dont know really anything about suspensions. I know that youdont want to mess with them unless you goto a professional or you know for sure what you're doing.

 

You didn't say what type of tires (both what you were on and what the take-offs are) - because different brands and have series have different profiles and that makes a difference also.

Before you change anything I would ride it for a seson or two, who knows you may just like it better with the taller tire.
The most likely effect is that the bike will turn in faster (agian this will depend on the difference in profiles, as well as the height), but you may loose a little feed back and the bike may want to push or run wide on exit. If this happens you can raise the forks (by dropping the front down) by 1/8 the height difference, if it's still doing it go another 1/8, etc...

But like I said ride it FIRST before making any changes.

 

Not much of a change.... That's a HUGE difference on a track bike.

 

The old tire was a Pilot Power the new tire is a Power Race Medium. From what I gather the extra 10% aspect ratio will raise the front end 1 inch. It should make the bike turn slower because it will increase rake & trail. Does this sound correct?

I could always leave the Pilot Power on the front. It's still in pretty good condition. Thoughts?

 

I theory yes, in reality yes and no, while it does increase rake & trail, it also raises the center of gravily, causing the bike to want to "drop-in" faster, the down side is that it takes a little more effort to do so and also makes it harder to flip direction quickly. Also going from a Pilot Power to a Power Race, the Race has a slightly more pointy or triangular profile and the Pilot Power does. This will also permote a faster drop-in.

It's tought to say yes change them or no don't without actaully seeing your tires and knowing you ability. But I've ridden (and even raced) on both types, I can honestly say either will do just fine on the track.

 

DON'T change them, i bought a second hand CBR600 F with a 120/70 tyre on and its garbage. You have ten mm of extra flex in the tyre and its shows, believe me. Its feels ok on the road and you can lean but eventually the more you lean the soggier it gets. I'm changing the tyre and its only done 1500 miles. Its a Pirelli Diablo with all the tread on and is getting taken off and sold or binned.

I've been having problems with the front end for a while, i've tried suspension adjustments, fork oil, handle bar and lever adjustments, pulling the yokes thru and the only thing we never thought was the tyre size. Its now been noticed and the next ride out i'm having is to change the tyre.

Stick with what the manufacturer says.