rear tire size

[Baldini]

The closer the profile of the rear tire is to the profile of the front the more easily and smoothly the bike will roll into and out of a lean.

 

IMO there is no question - the 170 turns better than the 180, matches front better, turns more smoothly. No downside I can see.

 

John T - have you tried a 170? I'd be surprised if, having tried one you wouldn't agree cos you describe the "linear" feel that the 170 will give over the 180...

 

Al, I'm using a 170/60. It's slightly larger diameter than 180/55, which, for me is a good thing, bit more wt to front, bit more ground clearance, tho only talking a few mm.

 

KB,Cymru

[al_roethlisberger]

Is that "as close as one can get" to the same height for the stock tire?

 

The reason I ask is that the new Ohlins adds a little height to the rear already(by having a more correct spring rate ) so I don't want to compound any height additions

 

al

[Guest captain nemo]

Captain Nemo pounded on his keyboard and the following questions appeared

 

You know, according to science, if I pound away at this keyboard for enough time, Hamlet will appear.

 

Ok, so who knows what alloy rims are available out there? Am I limited to Dymag and Oz?

[al_roethlisberger]

PVM as well....

 

I just know of OZ, Dymag, and PVM..... all very pricey.

 

I like the PVM wheels, but they're about $2500 for the pair. I think EMA USA had a sale on them a while back, and offered a few hundred off. You might check with them.

 

This would be my "ultimate" upgrade, lighter wheels, but just don't have that much dough at one time to drop on wheels

 

al

[Guest captain nemo]

OZ wheels are $1500 bucks. Problem is - the weight savings does not justiify the expense. They claim an average weight savings of only 4 to 5 pounds (no conversions for taking my thead down) PER SET. That isn't that impressive to me.

 

So, next question: I take it I can buy a Guzzi 5.5 inch wheel with no problem. Anyone know a ballpark price for a back wheel?

[al_roethlisberger]

I don't know the weight savings on the OZ wheels, but I do know that the savings for rear with the Dymags is significant(something on the order of 10lbs I think), and I think the PVM wheels might be similarly light.

 

The fronts aren't as big a savings, but anything more than a couple/three pounds is still a lot when considered at rotating weight.

 

Another issue, although minor, is the aesthetic.... some of the aftermarket wheels are very angular/etc and look great on many bikes, but IMHO the lines of the Sport/LeMans really lend itself to the 3 spoke curvey OEM Brembos and similar(like the Dymags).

 

Also, just a suggestion... stick with aluminum wheels for the street. Yes, the weight savings aren't as great, but one good pot-hole on a set of CF or Magnesium wheels... and you'll be buying a new one

 

I think the Dymags have a set with Magnesium spokes, but aluminum rims

 

 

Anyone have any real-world experience regarding durability with newer Carbon Fiber or Magnesium rims on the street?

 

 

al

[Guest captain nemo]

Carbon Fiber and Mag wheels are about $2500 a set. Too much. I'd pay 1500 if I could save 10 pounds.

 

Does anyone know what a regular Guzzi back rim goes for?

[Paul Minnaert]

Rear wheel 5.5 from a v11 le mans is 18 kg including tyre and disk. I have to wait till my pvm rear in in, I can tell you exact. The weight saving of the pvm front wheel is 1.5 kg, compared to v11 stock.

[gthyni]

Dymag no longer make rear wheels for Guzzi.

[Guest John T]

Found this chart from Dunlop. It shows rim size and proper tire size. Recommended tire size is in brackets.

 

A 170 tire is best (according to the charts) for a 5 inch rim. I still think a 170 on a 5.5 is just a little too small. I would worry about flattening the profile too much and running out of tread on the edges during hard leans. Could be wrong though and I'm very happy with the sizes I'm running.

 

http://www.dunlopmotorcycle.com/tirecatalog_tire.asp?id=82

[Guest captain nemo]

Yea, just found out Dymags are out - not making them for Guzzi anymore. OZ are aluminum and not a great weight savings.

 

If my 170 goes on a 5 inch rim then, yes, it is pinched, but not THAT pinched. Nevertheless, you've convinced me to go down to a 160 when I do the gearbox. OR I will buy a Guzzi 5.5 inch wheel and put on a 180. Guzzi DOES make a 5.5 inch rim don't they? I emailed the parts department, but did not get a reply.

[Admin Jaap]

The LeMans and Scura have 5,5" rear rims, so, yes.

[Guest John T]

Nemo, you have a 4.5 inch rim, go to a 160, the recommended size tire for that rim.

All Guzzis from 02 up have the 5.5 incher and the 180/55 tires.

 

Dymag probably got out of Guzzi wheel making after I threatenewd them with multiple lawsuits from pit bull lawyers after holding my money and no wheels for more than 10 months.

Pathetic work by both Dymag and Superbike racing in the states. But, they are really nice, light wheels.

[gthyni]

PVM makes the lightest, nicest Guzzi wheels.

They are not cheap,

2000-2300 euros per set

[Baldini]

a 170 on a 5.5 is just a little too small. I would worry about flattening the profile too much and running out of tread on the edges during hard leans

John T,

I ran the 180 on 5.5" rim, felt the back was always slow to turn in, bike didn't lean in a "linear" way. By the way you describe the symptons of an overwide tyre I am sure you would prefer the 170, if you got to try one. Profile on the 180/55 actually appeared flatter than the 170/60 when fitted & went to the edge v quickly with still a fair bit to go on front. The 170 certainly feels more curved when riding, leans much more at same rate as front. I don't know a lot about tyres, but is a 60 aspect ratio always going to be more curved than a 55 anyhow? (presuming correct rim size). 170/60 is narrower but taller than a 180/55 - suggesting it would be more curved but I don't know if that extra height is in the sidewall height or the tread profile...? Another thing ...I have Pirellis, does rec'd rim size differ with manufacturer? I ride to the edges of the tread f & r. I changed BT020s 180 to Diablo 170 so some of the feel may be down to tyre and although I don't think so, I can't be sure you wouldn't ride off the edge of the rear easier on 170, but before that point if it does come, the balance of the bike when leaning is much better. Anyone tried a 180 in a higher aspect ratio than 55?

Anyone be definitive about this?

KB, Cymru