Tonti: 120/80-18 Rear and 110/80-18 Front - Anyone?

[Groover]

Searching tire options, I found this thread where someone said that the original Tonti frame was designed to use 110/80-18 Front and Rear. Is that correct?

(It's on this page:)
http://www.advrider.com/forums/showthread.php?t=605091&page=36

I've read up a lot on tires, and most around here say to stick with the 110/90-18 rear and 100/90-18 front for best all around performance.

Has anyone here used a 120/80-18 (Rear) and 110/80-18 (Front) combination on a short-base Tonti? If so, how did the bike behave?

Sorry, I think this is my 3rd tire thread on this board.... But isn't that what we all want to see? Same topics over and over, but slightly different?  :BEER:

Thanks again!

[Sportsterleroy]

I think that size is on my Convert , and I am replacing them with that size Shinko brand. Will look in the garage and add more later today.

IF it is i rode it about 500 miles fine last season, noticing no unusual qualitys
 

Leroy in Cleveland

[mtiberio]

I am currently running a 110/80-18 on the front on my tonti in an attempt to lower the bike without cutting the seat. It works.

I see no issue with running a 120/80-18 on the rear. I never have, but I have run just about every other width/aspect ratio combo you can imagine. I don't see that as anything special.

[Groover]

Thanks for the replies so far. I've also noticed that some of the weigh ratings are better on say a 120/80 profile versus a 110/90 profile, which I thought was odd. I ride two-up mostly, so that's something I also need to consider.

[mtiberio]

obviously pay attention to recommended rim widths and permissable rim widths. I find the dennis kirk web site has the best tire info of any of them. they have an overview and specs tab which provide whatever info is out there.

[mtiberio]

just looked, and none of the 120/80-18s I looked at go down as small as a 2.15" rear rim, stock on mid-70's tontis...

so I wouldn't run it on a 2.15" rim. a 110/80 might be the hot lick...

[PeteS]

I tried a 110 front on my LeMans but prefer the 100 for the quicker handling. Wider tires might be OK on a touring bike though.

Pete

[Moto]

The OEM T3 owner's manual I'm looking at right now has this dual specification, in both inch and metric sizes:

Front: 3.50 H x 18 H     or     100 / 90 H x 18 H
Rear:  4.10 H x 18 H     or     110 / 90 H x 18 H

Interestingly, if you convert the inch specs to mm, you get 88.9mm for 3.50 inches at the front, and 104.1mm for 4.10 inches at the rear. This suggests using a 90/90 at the front instead of the 100/90. I did try that and found the steering was quicker, as expected.

I also had a 120/90 rear on at one time, with a 100/90 front, I think. That seemed to hurt handling.

I use the 100/90 front 110/90 rear combination now, per the book, though I think the 90/90 front is also good.

I think it's reasonable to say the T3 was not designed for 110/90 front and rear, since the spec called for 100/90 front or an inch size closer to 90/90.

[acogoff]

     I run a 110/90-18 on the T3 front and rear and like the bus like handling with our straight roads and seemingly constant crosswinds.

[NCAmother]

I run a 110x80 front and 130x80 rear.  Any bigger and you'll have to modify the swingers.

[Groover]

I run a 110x80 front and 130x80 rear.  Any bigger and you'll have to modify the swingers.

What brand are you using?

[Triple Jim]

I recently installed a 130/80 on a 2.5" rim, to replace a 120/90, and found that its width was identical!  Then I realized that the 130/80 was designed for a wider rim, so when it was squeezed onto the 2.5" rim I have, it was reduced in width to the same as the old tire.  Even though the 2.5" rim is at the low end of the recommended rim width, it doesn't necessarily give you what you expect.  All I got was chicken strips from the extra tread wrap.

[Groover]

I've noticed some brands where say a 120/90 will be wider than a 120/80 of the same line and placement (rear for example). As many have said on this board, it really does depend on the brand. I compared Bridgestone's BT-45 4.00 Rear and 3.5 Fronts (which are supposed to be the closest to the factory Tonti sizes, at least according to the T3 manual) which now the equivalents are 110/90 Rear and 100/90 Fronts (according to the G5, Etc. Manuals), but the BT-45 are to my findings closer to the 120/90 Rear and 110/90 Fronts in the Pirelli Sport Demon sizes for example, so who knows. The standard isn't much of a standard is what I'm learning...

[NCAmother]

What brand are you using?

I'm running the BT45's aka battle axes. Going 140, I'd recommend a wider rim and some swing arm work.  I had a 140 mocked up, and it looked pretty good, but was rubbing on the swingarm and the 2.15 wheel was too narrow. so I compromised with a  130.   Wide, but not obnoxious.

[guzzigray]

Try the new Continental radials.

https://www.conti-online.com/www/motorcycle_de_en/themes/motorcycletires/conti_classic_en/classic_attack_en.html

I have the race version and they are amazing. The 110 front looks more like a 100. Great profile.

[mtiberio]

I'm running the BT45's aka battle axes. Going 140, I'd recommend a wider rim and some swing arm work.  I had a 140 mocked up, and it looked pretty good, but was rubbing on the swingarm and the 2.15 wheel was too narrow. so I compromised with a  130.   Wide, but not obnoxious.

hate to tell you but 130 is too wide for a 2.15" rim. As far as I know, the only 130 made that includes a 2.15" rim in the list of permissable rims is a 130/650-18 "cheater" race tire made by Avon that has special cantilevered (stiff) sidewalls to make up for the fact that the tire would otherwise be undersupported. They made this tire because vintage race organizations often limit rims to 2.15" widths.

[mtiberio]

Try the new Continental radials.

https://www.conti-online.com/www/motorcycle_de_en/themes/motorcycletires/conti_classic_en/classic_attack_en.html

I have the race version and they are amazing. The 110 front looks more like a 100. Great profile.

I have my eye on those... the 110/90-18 is designated a rear, not like that would stop me from using it on the front, but you called it a front. Did you find a front?

http://www.motorcycletiresmaniac.com/conti-classic-attack-motorcycle-tires.html
http://www.motorcycletiresmaniac.com/conti-road-attack-2-cr.html
http://www.dimecitycycles.com/catalogsearch/result/?q=classic+attack&x=0&y=0
https://www.conti-online.com/www/motorcycle_de_en/themes/motorcycletires/conti_classic_en/road_attack_en.html

[guzzigray]

I have my eye on those... the 110/90-18 is designated a rear, not like that would stop me from using it on the front, but you called it a front. Did you find a front?

http://www.motorcycletiresmaniac.com/conti-classic-attack-motorcycle-tires.html
http://www.motorcycletiresmaniac.com/conti-road-attack-2-cr.html
http://www.dimecitycycles.com/catalogsearch/result/?q=classic+attack&x=0&y=0
https://www.conti-online.com/www/motorcycle_de_en/themes/motorcycletires/conti_classic_en/road_attack_en.html

My apologies for any confusion. I use the 'CR' which is the endurance race tire. 130 rear 110 front. Absolutely amazing tires. I've done 2 race weekends and 2 track days on one set and not so much as a slide and they are super sticky. Compared to the Avon classic race tires they are far superior.

I found info for street fronts here:

http://www.bikebandit.com/tires-tubes/motorcycle-tires/conti-classic-attack-motorcycle-tire

I would go with a 90/90 front and a 110/90 rear. I love skinny tires on my street Guzzi.

[mtiberio]

My apologies for any confusion. I use the 'CR' which is the endurance race tire. 130 rear 110 front. Absolutely amazing tires. I've done 2 race weekends and 2 track days on one set and not so much as a slide and they are super sticky. Compared to the Avon classic race tires they are far superior.

I found info for street fronts here:

http://www.bikebandit.com/tires-tubes/motorcycle-tires/conti-classic-attack-motorcycle-tire

I would go with a 90/90 front and a 110/90 rear. I love skinny tires on my street Guzzi.

what sort of rear rim (width) do you have on your track bike?

[guzzigray]

what sort of rear rim (width) do you have on your track bike?

It's 3.5 but I use MK4 swing arm which is wider.

[Groover]

Those do look great. I'd use skinny tires if I were riding solo and such, but I mostly ride two-up (80% of the time). Wouldn't a little fatter tire be better to absorb a two-up riding situation?

[guzzigray]

Those do look great. I'd use skinny tires if I were riding solo and such, but I mostly ride two-up (80% of the time). Wouldn't a little fatter tire be better to absorb a two-up riding situation?

I think you'd be fine with a skinny rear tire. I've ridden two up long distances no problem with a 110.