120/60/ZR17 vs 120/70/ZR17

[tbonehedge]

I have a 2008 Sprint ST and just purchased tires online. I ordered the wrong size front, I bought a 120/60/ZR17 when I should have bought a 120/70/ZR17. Did I screw myself, will this tire work for me. I know it will fit the rim and the ride height will be a little different, is there anything I should be worried about if I mount this tire to my bike? I don't want to have safety/handling issues.

[Mad Max]

It will probably be ok. My SV was originally equipped with a 60 series and it has a 70 series now.

You might notice that the bike is a little bit more sluggish to turn-in and the reduced clearance between the tire and the front fender might cause some rubbing.

[tbonehedge]

You say sluggish-in turn and possible rubbing the fender, so a 60 series tire is bigger than a 70 series tire? that doesn't sound right to me.

[DoubleRGirl]

the 60 is smaller, i used to run a 60 profile to make the front of my bike a little lower. i believe i have a 60 profile on the front in my avatar pic, i didn't have any issues but i definitely used more of the tire

[tbonehedge]

Can one of the many tire vendors we have on this site please chime in? What are the issues I would have going from a 70 to a 60? I know ride height would be less and there is more chance of denting the rim if I nail a curb/pothole. Would the contact patch from the tire to the road be less? I'm not sure it would be, the side to side dimension is the same (120) so why would the contact patch be less?

[mi1knc0okies]

google is your friend homie. http://www.ehow.com/how_5819218_read...ire-sizes.html

[nt650hawk]

Bike car it is all the same thing


Sidewall Aspect Ratio

Typically following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio.

P225/50R16 91S

The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The higher the number, the taller the sidewall; the lower the number, the lower the sidewall. We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall.

[mi1knc0okies]

You shouldnt have any safety issues but may notice the bike handling a lil differently. The reason the bike comes with a 120/70 is because the factory has deteremined that to be the best size for performance and handling after hundreds of hours of testing.

[OreoGaborio]

Just put it on. It's very likely that you won't notice any difference.
If you don't like it, just buy a 70 when it wears out.

[schleppy]

I went from a 60 to a 70 on my SV. It slowed the turn in a hair, so I raised the forks up to make up for it. It was fine.

[tbonehedge]

Just put it on. It's very likely that you won't notice any difference.
If you don't like it, just buy a 70 when it wears out.

Thats pretty much what I'm thinking. I just wanted to make sure before I mounted it and couldn't return it.

[OreoGaborio]

Werd.

Well it may change the way the bike feels a LITTLE bit, but it certainly isn't going to be a safety issue.

[Rada]

I did the same thing on my last set of skins. I ended up with a 60 on the front. It was not a big difference. I didn't have to worry long. It was gone in about 300 miles.

[Mad Max]

It will probably be ok. My SV was originally equipped with a 60 series and it has a 70 series now.

You might notice that the bike is a little bit more sluggish to turn-in and the reduced clearance between the tire and the front fender might cause some rubbing.

You say sluggish-in turn and possible rubbing the fender, so a 60 series tire is bigger than a 70 series tire? that doesn't sound right to me.

You're right, my mistake, I misread your original post and what I said is the exact opposite of what you might experience.

By the numbers, the smaller front tire (60 series) is going to lower your front end by (120* (.70-.60))=12mm=0.47inches. The 'drop' is going to decrease your rake, and trail by small amounts which will probably result in more responsive and less stable handling. For some bikes that might be a big change, for your's it might not be that much - I don't know enough about it. If I had made the same mistake, I would keep the tire and lower the forks through the triples by ~5mm (bringing the front end back up) and be cautious about how it handled until I got used to it. Hope that helps and sorry about the confusion.

[OreoGaborio]

The problem with your math is that aspect ratio has nothing to do with the PROFILE of the tire.... so really, you could be 100% right.... or you could be 100% wrong depending on the shape of the actual tire carcass.

[Mad Max]

The problem with your math is that aspect ratio has nothing to do with the PROFILE of the tire.... so really, you could be 100% right.... or you could be 100% wrong depending on the shape of the actual tire carcass.

Good point, Pete. I didn't think of that.

If you wanted to get real difference in height then maybe a direct reading is necessary?