Now as I understand it, this ain't strickly the done thing, but a fair fiew of you do it.
Was wondering how folks had found them. Any significant diadvantages or advantages.
Please note I'm not interested in make and model opinions but your honest opinion of fitting both sizes.
I pressume a 180 / 55 on a 170 rim would be pinched in, increasing its profile height pushing its aspect ratio up towards 60,( the standard on a 170) and giving it a degree or so more lean before reaching the edge. From my experience with conti ra2's there comparatily high profile gives them a very lively quick to turn feel, but increases centre wear (also helped by soft centre).
Probably gonna put a set of bridgestone s20 which do 170's but dunny sportsmart, the other top contender only do 180's.
Any help from actual testing much appreciated

_________________
Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth

I'm no knee-down biking god, but I have tried both on my Tuber over 12 years, it came on a 180, but I would now only ever use a 170.
Pros of a 180: Looks sexier
Pros of a 170: Turns much quicker
Can't tell you about relative lean angles cos I've never stopped to measure them.

_________________
'98 M2 Razorback, it's a keeper.

I have a uly with a standard 180 tyre ( Bridgestone ) and I comfortably go to the edge and maybe even beyond it, I also have an X1 with a standard 170 tyre ( Bridgestone ) now I ride the X1 for fun and I can only get to around 10mm from the edge of the tyre.
People have in the past looked at my X1 and told me I must be a chicken because of these strips!
Well in my mind the uly is over tired as its tyre is to wide, I know I corner harder and faster on the X1.

Thats my opinion for what it's worth anyway!

I went to view an S1 with a view to buying and it was fitted with a 190

The bike felt awful, but that was more to do with the loose headraces and general poor state...

That S1 is now owned by another forum member

_________________
08 Specialized Langster

I'm not going mad then.......Knee sliders scuffing and conti ra2's 170 / 60 will still be a good 10mm from the edge. As for what it looks like couldn't give a piss .....nimble ness and grip's what matters to me, 180's just give better choice. Currently trying to find something with a bit more dry grip than the conti's that keeps its profile longer and lasts a little longer hence the sportsmart / s20 - bt016pro conundrum. Thanks for the info

_________________
Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth

Hmmm.....I'm no riding god and have never managed to get rid of the chicken strip on any of my 170 shod tubers.......but I know a few that have, most notable are OF and Squiz, both of whom regularly had molten rubber deposits almost down to the rim

Restone, have you considered the Mich Pilot 2CT's ?

_________________
Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR