4.5" rear rim into 02 Scura

[Guest ratchethack]

John, I'd really appreciate your experinece on this and a little more detail please. My shop manual spec's a 170 for the stock 4.5" rim. Are you saying that your experience is that they spec'd it too aggressively, and that better overall performance may be had with a 160?

[Ralph Werner]

Baldini, I'm running an Avon 46 - 170/60 on that rim. It seems to fit fine and the handling might be slightly better (but I'm no metal scraper). So far, I like the Avons.

[belfastguzzi]

Re Ratchet,

 

isn't that the opinion that was given 'everywhere' – that those bikes were supplied with a tyre that was too big for rim? Then eventually MG moved it up to a wider size.

[Baldini]

160 on a 4.5 inch rim ...Been there done that.......

John,...and what do you reckon? Does it work well?

 

I'm pretty happy with the handling of the 170 on the 5.5" rim, my concern is that cos of the flatter profile it will run off the edge of the tread earlier than a 180 (or 170 on a narrower rim). Is a 5" rim maybe optimum for the 170? I want to keep good round profile, as the 4.5" rim is available & fits, that rim w/ 160 sounds like the way to go....?

 

Thanks.

 

KB

[Baldini]

Ralph,

 

Why did you go to the smaller rim?

 

KB

[Guest John T]

Is a 5" rim maybe optimum for the 170? I want to keep good round profile, as the 4.5" rim is available & fits, that rim w/ 160 sounds like the way to go....?

 

Thanks.

 

KB

The original sport 1100's had a 4.5 inch rim and a 160 tire...worked fine.

 

Guzzi for some reason put a 170 on the rear. This pinched the tire too much distorting the profile and causing uneven handling when leaned over. No matter what you did you could not use all the tire as evidenced buy the 3/4 inch chicken strip on the tire. (parts dragged first)

 

Tire companies spend millions on tire design and spec rim sizes to keep the contact patch optimal. Too little or too big a tire on a rim will ruin the handling of tires.

 

Find a chart that specs tire sizes to rims. (I don't have one handy) There is little room for variance. From what I have seen on these charts a 4.5 inch rim likes a 160. A 5 inch rim likes a 170 and a 5.5 inch rim likes a 180.

 

I went to a 5.5 inch Dymag (10 pound lighter) and a 180 rear. Fits fine and handles better than I push it on the street. I am over 225 pounds and my bike puts out over 70 lbs of torque on a good day. I want as much rubber back there as I can get....and being that I am a poser I find chicks dig a guy with a fat rubber.

[Ralph Werner]

Baldini, I swapped rims with Joe Camarada because i wanted gold powdercoat. It seemed easier than getting my rims done and at 64 I'm not a performance freak.

[Baldini]

John & Ralph, thanks for the info. KB