Can a 120/90-18 "rear" bias-ply tire be mounted on the front?

[brider]

I've gotten a lot of good info from my "best rain tire?" thread, and am now looking at the Avon AM26 tire. But, the closest size they advertise for the "front" is a 110/90-18, while my preference is a 120/90-18. Height difference between the two sizes would drop my front end about .72 inches, which I don't want to do, so.....

What about a 120/90-18 "rear" tire? As long as the ply design, speed rating and tread pattern is the same as the AM26 front, what could be wrong with doing this? I'd find it easy to believe that a manufacturer might call a 120/90-18 a "rear" tire because so few models spec them for the front.

Thoughts?

[Aaron D.]

Back in "the day" I knew several racers running LeMans (early) with Pirelli Phantom rears on both wheels. No reason not to if you want to try, then YOU can answer the question!

[Chuck in Indiana]

Brider, I'm familiar with the "bigger is better" think in the US.. but bigger is *not* better on motorcycle tires. I know you said that your Cal2 stock front tire is a 120/90.
But, it's not.
Guzziology and much experience here on WG says that it is 110/90. The stock front wheel on a Cal2 is 2.15 inches. The minimum wheel width for a 120/90-18 is 2.5 inches. It's just plain too wide for the wheel. The effects of a too wide tire are well known.
What Kirby 1923 said is spot on.

[chuck peterson]

Use to do that 37 years ago with my r60...you could just swap the wheels to wear out the unused front on the rear...of course the squared off rear was now on the front

I think Avon has a tire that'll go front or back depending on the direction you mount it...unknown about wet weather ability or distance

...ps...just checked, no 120 size for the universal front/rear...but it's there in a 110/90

[Antietam Classic Cycle]

Brider, I'm familiar with the "bigger is better" think in the US.. but bigger is *not* better on motorcycle tires. I know you said that your Cal2 stock front tire is a 120/90.
But, it's not.
Guzziology and much experience here on WG says that it is 110/90. The stock front wheel on a Cal2 is 2.15 inches. The minimum wheel width for a 120/90-18 is 2.5 inches. It's just plain too wide for the wheel. The effects of a too wide tire are well known.
What Kirby 1923 said is spot on.

FWIW, the owner's manual states 120/90-18 for both ends. However, I wouldn't go that wide on a front tire.

[brider]

I'll do some verification for my own education, but if the minimum rim width for a 120/90-18 is larger than what I have on the front of my Cal 2, then I have a problem that I think I'll have to address on both ends.

I suppose I should do a search, but can someone explain briefly what the downside is of running a 120/90-18 (stock size) on the front is? Been running that size for 45k miles with no ill-handling issues that I can detect.

Correction: I originally stated a 110/90 would drop my front end .72....that was wrong, it would drop exactly half that, the .72 number was the total diameter difference.

[kirby1923]

 If you have been running a front 120/90 bias tire:

1. You have found a company that makes a 120/90 bias front.

2. You have found a company that makes a bi-directional tire.

3. You have disregarded the arrows for a rear and run it on the front.

4. You have run a rear on the front but in reverse...(I hope).

No offence but you asked for thoughts........... ...good luck.




Make Model
 Moto Guzzi California II

Year
 1983-86

Engine
 
Air cooled, four stroke, V twin, longitudinally mounted, OHV, 2 valve per cylinder.
 

Capacity
 948.8
Bore x Stroke 88 x 78 mm
Compression Ratio 9.2:1

Induction
 Dellorto VHB 30 Carburation Main Jet 125 Carburation Idle Jet 50 Fuel Minimum Octane Rating 97 Pilot Screw Setting 1.5

Ignition  /  Starting
 -  /  electric

Max Power
 59 hp @ 6750 rpm 

Max Torque
 6.6 kgf-m @ 5750 rpm

Transmission  /  Drive
 5 Speed  /  shaft

Front Suspension
 Telescopic forks

Rear Suspension
 Dual Koni shocks 5-way preload

Front Brakes
 2x 300mm discs 2 piston calipers

Rear Brakes
 Single 275mm disc 2 piston caliper

Front Tyre
 110/90 V18

Rear Tyre
 120/90 V18

Dry Weight / Wet-Weight
 250 kg / 260 kg

Fuel Capacity
 28 Litres
 

[Chuck in Indiana]

FWIW, the owner's manual states 120/90-18 for both ends. However, I wouldn't go that wide on a front tire.

Ahh but, Charlie. That's a Guzzi manual. 

[brider]

Front Tyre
 110/90 V18

Rear Tyre
 120/90 V18

I found this same data on the MCS website, never saw this site before, or searched for this info. How reliable is this, and is this supported anywhere else? I have an OLD version of Guzziology, are "correct" tires sizes tabulated?

Thanks for this info, kirby1923

[kirby1923]

They are accurate for my machines so far but????

I am curious about who?? makes a front/ bi-directional bias 120/90??? If you can't find one there is a  pretty good chance that the info is accurate.

[brider]

Dunlop, Shinko, Kenda, Avon, Metzler, Bridgestone, etc, all make 120/90-18 tires, but I wasn't looking for a bi-directional, I was looking at the Avon AM26 120/90-18 rear to be used on the front, which I now realize would be impossible per the logic put forth in this thread. Glad I asked!

I might have realized it after I bought the tire, but the tread is definitely directional, and if I swapped rotation direction to satisfy internal ply design req'mnts, the grooves would be wrong.

I will now definitely look for a "front" tire, size TBD.

[rocker59]

Correction: I originally stated a 110/90 would drop my front end .72....that was wrong, it would drop exactly half that, the .72 number was the total diameter difference.

and a 0.36 drop in ride height is negligible, so shouldn't be an issue for you.

Wheel width you have vs. recommended wheel width for the tire you choose is more important.

and, as others have said, wider is slower on the turn-in. 

[Antietam Classic Cycle]

Ahh but, Charlie. That's a Guzzi manual. 

Then the brochure is incorrect too:
http://thisoldtractor.com/moto_guzzi_more_topics_brochure_-_moto_guzzi_california_ii_-folded_style_brochure-.html

[mtiberio]

Avon has a fitment chart. They say the min rim for their 120/90 is 2.5", and recommended is 2.75"

[redhawk47]

Back to your original question, rear tire on the front, but for a different bike.
I have a V7II Stone; front tire is 100/90-18, or, per V7III spec, 110/80-18, tubeless.
I want to mount dual sport 80/20 tires and keep it tubeless. I have found only one tire (with a matching rear) that fits, Kendo K761.
In my research I found another tire which seems to offer better performance in the right size, but it is a rear tire: Avon AV54 TrailRider.
Advice I have received is to mount the tire backwards. Thread, and construction, will now be in the correct direction. On dual sport tires the tread pattern on the top of the tire points to the center of the bike, front and rear. Checking the specs I noticed that the rear tire has more tread depth than fronts; could affect handling. I don't know about thread depth on your road tires.
I wrote Avon tech support about running the rear on the front; this was their response: "We cannot recommend using the rear tire for the front but we have seen a lot of people do it without any problems."
PS: There is another set of tires that fit: the OEM tires on the Stornello, but I don't care for them.

[mtiberio]

Don't make me...

you can go here: http://www.avonmoto.com/products/adventure-sport/trailrider

to see this:

[mtiberio]

Have you looked at Heidenau's?

http://heidenautires.com/dual-sport-tires/

[brider]

OK, just to follow-up on my strange original question:

I ended up putting the Avon AM26 Road Rider 110/90-18 on the front of my Cal 2, noting that it IS bias-ply AND front/rear compatible.

But WOW I'm glad you guys clued me in to the correct front tire size after running a 120/90-18 all these years; what a HUGE difference a change in size made! Made the bike practically "flickable" in corners. Better-handling all-around than the Shinko I was running, too.

[Triple Jim]

But WOW I'm glad you guys clued me in to the correct front tire size after running a 120/90-18 all these years; what a HUGE difference a change in size made! Made the bike practically "flickable" in corners. Better-handling all-around than the Shinko I was running, too.

I'm sure the smaller size helped, but Avon Roadriders are really great handling tires in my experience. 

[Antietam Classic Cycle]

I'm running a 100/90-18 Shinko 230 on the front of my Convert. Nothing wrong with Shinkos (a lot very right IMO) and the 100 helps alleviate the heavy steering feel I've always disliked about Tonti-frame Guzzis with 18" wheels. I'd never think of putting a 120 on the front of a Tonti (or Loop).

[troyhamilton]

I am running a 4.00 18 rear on the front. run rears backwards on front. run fronts backwards on rear...

[Chuck in Indiana]

You running a back rim on the front, too?

[troyhamilton]

ha ha. no but i rode it backwards yesterday, lol rolled backwards!

[brider]

I'm running a 100/90-18 Shinko 230 on the front of my Convert. Nothing wrong with Shinkos (a lot very right IMO) and the 100 helps alleviate the heavy steering feel I've always disliked about Tonti-frame Guzzis with 18" wheels. I'd never think of putting a 120 on the front of a Tonti (or Loop).

I've used the Shinkos as my last (2) sets, and can't complain either except I definitely felt wandering on the crack-repairs on my exit ramp that I DON'T feel on the Avon, and the Avon is a smoother ride.

I still have a Shinko 120/90-18 on the rear because that's what the Guzzi info specifies, but I'm wondering if I should go ahead ahead and swap that, too for a 110/90.