Skeeve Posted March 2, 2006 Share Posted March 2, 2006 O.K., so there's been lots of discussion about how the 170/60 rear tire makes for slightly better handling Guzzi than the stock 180/55 size. But has anyone tried a 120/60 front vs. the (slightly oddball) 120/70 size? Is the difference substantial? The difference in axle height works out to about 12mm; I haven't done the trig, but it should work out to slightly decreased rake & slightly greater trail figures. [Kinda like the old "dropping the forks 1/2" in the triple trees to quicken the turn in..." squid trick] Just curious, since the industry standard seems to be the /60 profile, so those tires will usually be cheaper. Ride on, Link to comment Share on other sites More sharing options...
Guest mtiberio Posted March 2, 2006 Share Posted March 2, 2006 there is nothing odd about a 120/70. 99% of the sport bikes in this world run them. I'd stay away from the 120/60. very poor rim protectors, and you'll dent your rim on the first pothole. Link to comment Share on other sites More sharing options...
Guest ratchethack Posted March 2, 2006 Share Posted March 2, 2006 Wot Mike said. I wouldn't want to put one on and then actually have to wear it out. The considerable rear weight bias of the Guzzi chassis wouldn't tend to play too well with the /60's reduced contact patch approaching the limit. BAA, TJM, & YMMV Link to comment Share on other sites More sharing options...
dlaing Posted March 3, 2006 Share Posted March 3, 2006 Wot Mike said. I wouldn't want to put one on and then actually have to wear it out. The considerable rear weight bias of the Guzzi chassis wouldn't tend to play too well with the /60's reduced contact patch approaching the limit. <_> BAA, TJM, & YMMV 80764[/snapback] I think the /60 would actually have an increased contact patch...a little shorter, but wider contact patch. The only thing I'd be concerned about is geometry and weight bearing. I'll bet the weight bearing rating is not very different, and the geometry could probably be compensated for in the fork adjustment. But it would feel different. Link to comment Share on other sites More sharing options...
Baldini Posted March 3, 2006 Share Posted March 3, 2006 I recently spoke at length with a man from Michelin. Pressures & air volume being critical to the way any tyre will work, he said that fitting undersized tyres would give reduced air volume & this could promote overheating. He also told me a lot of other interesting stuff about sidewall performance being compromised by profile changes, & contact patch sizes but it went in one ear out the other.... I dropped the clamps on my 02 Scura & it worked a treat - steers much better. Ground clearance could be an issue lowering the bike. KB Link to comment Share on other sites More sharing options...
antonio carroccio Posted March 3, 2006 Share Posted March 3, 2006 Keith, it's not clear to me, if you have or don't a front tyre in the size 120/60. Link to comment Share on other sites More sharing options...
Baldini Posted March 3, 2006 Share Posted March 3, 2006 Keith, it's not clear to me, if you have or don't a front tyre in the size 120/60. 80829[/snapback] Antonio, no I haven't tried 120/60 - I am happy with 120/70 front (IMV the problem's at the other end..). I think gythni tried a 120/60 & doesn't recommend it (but he has short frame bike). KB Link to comment Share on other sites More sharing options...
dlaing Posted March 4, 2006 Share Posted March 4, 2006 I recently spoke at length with a man from Michelin. Pressures & air volume being critical to the way any tyre will work, he said that fitting undersized tyres would give reduced air volume & this could promote overheating. 80826[/snapback] That makes sense. But if you go undersized and run at a higher pressure, the overheating should not be a problem. If you had a choice of 120/80 or 120/60, what would you choose? Personally I am undecided, but probably leaning more towards the 120/80. If you had a choice of a 16 or 18 inch front wheel, which would you pick? Link to comment Share on other sites More sharing options...
Guest mtiberio Posted March 4, 2006 Share Posted March 4, 2006 stop trying to be smart, and run what the factory says to run in the riders handbook. the engineers at the factory rarely get tire size wrong. That makes sense.But if you go undersized and run at a higher pressure, the overheating should not be a problem. If you had a choice of 120/80 or 120/60, what would you choose? Personally I am undecided, but probably leaning more towards the 120/80. If you had a choice of a 16 or 18 inch front wheel, which would you pick? 80952[/snapback] Link to comment Share on other sites More sharing options...
Baldini Posted March 4, 2006 Share Posted March 4, 2006 ...But if you go undersized and run at a higher pressure, the overheating should not be a problem..... ????eh???? - couldn't understand the relevance of other questions either... ....stop trying to be smart, and run what the factory says to run in the riders handbook. the engineers at the factory rarely get tire size wrong.... So you figure the V11 needs a 180 rear tyre? For what? KB Link to comment Share on other sites More sharing options...
Guest ratchethack Posted March 4, 2006 Share Posted March 4, 2006 ????eh???? - couldn't understand the relevance of other questions either... So you figure the V11 needs a 180 rear tyre? For what? KB I agree, Keith. The factory-issue (and manual recommended) 180/60 rear was clearly wrong for the 5.5" rim. The replacement should always be a 170/60. Likewise, the factory-issue (and manual recommended) 170/60 rear was clearly wrong for the 4.5" rim, the replacement for this should always be a 160/60. This appears to have been some kind of a misguided "comittee choice" styling statement. By my own experience and that of many others, it makes a significantly positive handling difference when you get it right, particularly when you also get the spring rates and laden/unladen sags right. IMHO, the 120/70 is/was correct for the front as issued. If you mess with the aspect ratio here, you'll likely be compromising handling - mostly due to a smaller contact patch, which I believe happens going either direction from stock issue. BAA, TJM, & YMMV Link to comment Share on other sites More sharing options...
Skeeve Posted March 5, 2006 Author Share Posted March 5, 2006 Well, thanks for all the input! As usual, the v11LM.com community comes thru in fine style with great info; as luck would have it, however, the point is moo. You know, like a cow's opinion - it doesn't matter. It's moo... Why? Because the following promotion is only for a 120/70 front tire! [Geez, doncha wish I'd read the fine print sometimes?] [sorry for those outside the USA, I think it's only good Stateside...] BOGO Pirellli Strada Front tire promo offer Potential source for the 170/60 [or 180/55 for the "follow the owner's manual at all costs" sort (which I usually am, but this forum has all the answers, so I trust the 170/60 recommendation)] - try swmototires Be advised that Pirelli has allocated a set number of tires to the promotion, so you'll have to act fast! Link to comment Share on other sites More sharing options...
O2 V11 Posted March 5, 2006 Share Posted March 5, 2006 "I ran mine last summer on 120/60-17 Pirelli dragon corsa, no trouble with the front. but watch out many tyres with the lower profile are made for lightweight bikes like 600cc sportbike or supermotard bikes. Our V11s needs a more stable tyre at high speeds." This is gthyni's response to a similar posting I made last year. From the Continental tyres website: In the ContiForce range, the difference between a 120/70 and 120/60 is, the 60 tyre has a load rating of 218kg compared the 70 tyre's 236 kg. The rim width recommendations are the same as is the air pressure. Another difference being a 24mm reduction in diameter for the 60 tyre. Given that the V11 has an accepted rearward weight bias I cannot see fitting a 120/60 front would cause any major problems. Can anyone state how much weight is on the front wheel, I broke my bathroom scales trying to find out... My own experience in downsizing the rear tyre, which led to making my bike a better handling one, makes me keen to experiment with the front tyre sizing as well. Rob Link to comment Share on other sites More sharing options...
dlaing Posted March 5, 2006 Share Posted March 5, 2006 ????eh???? - couldn't understand the relevance of other questions either... : 80987[/snapback] I just think it helps one predict how it will handle if you visualize going both smaller and larger rather than just visualizing going smaller....atleast it became clearer me. Many of us have more familiarity with 18inch wheels, and going to a 120/80 would make the bike handle more like that. I would not say it is right or wrong to go with a 120/80 or 120/60 rather than the 120/70, unless you run into load rating problems. But I think if you want it to "feel" more stable, and suck up potholes better, go with a higher profile....the more I think about it, the more I like the idea of a higher profile... If you want it to be more nimble go with the lower profile. If you like it the way it is, stay with it. Link to comment Share on other sites More sharing options...
Baldini Posted March 5, 2006 Share Posted March 5, 2006 I agree, Keith. The factory-issue (and manual recommended) 180/60 rear was clearly wrong for the 5.5" rim. The replacement should always be a 170/60...../quote] Going from stock 180/55 BT020 to 170/60 Diablo gave huge improvement in turn in. Different profile, narrower tread, wider diameter - not sure what part is played by each...No downside except I was concerned that 170 stretched over same rim as 180 (both art recommended fitments to 5.5" rim) would flatten profile & run off tread earlier. I've never heard a conclusive answer about this but most seem to think there wouldn't be much difference in it. I found already the edge comes very early so went back to a 180/55 Diablo. Doesn't turn as good as 170 but still much better than original fitment BT020. I bought a 4.5" rim so when I ever get time to sort it I'm going with that & a 170 or 160 - I spose the same thing applies there as with the 5.5" rim sizes. For me higher aspect ratio is a plus at rear - anything to shift a bit more weight forward & help ground clearance as I already lowered front. I'm no expert in this stuff - all I know is what I've found on this bike. Always run Tontis till getting Scura - on stock 18" skinny sizes which have never, ever been an issue, seemingly perfectly matched end to end & to bike. Like a lot of things in more recent Guzzis, I think wheel & tyre sizes are a "triumph of form (fashion) over function" (they work well in the pub car park). KB Link to comment Share on other sites More sharing options...
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