QUESTION ABOUT FRONT TIRE SIZE

[1NorthRyder]

So  I bought my Valk last year and just ran with the front tire that was on it without checking the tire size. It's time for a new tire so I started doing research. OEM size is 150/80 R17 but the tire on the bike is 150/60 R17, a full 2" smaller. I never had an issue riding but was wondering from the collective if there was an advantage (other than throwing off the speedometer) for having the smaller tire or should I return to the OEM size?

[Chrisj CMA]

Return to OEM. It will handle better.

Also keep air pressure up: 40 front 42-44 rear

[pago cruiser]

Interesting question.  3 things:

1.  The Legacy Valk has rake/trail values of 32 degrees and 6".  Rather cruiser-ish values. Which means they are generally more stable than sport/sport tourer types of bikes with trail values of 4" or so.

A 2" diameter smaller front tire is enough to change your trail by about 1" - that is significant.
Here's a fun little calculator:
http://www.datamc.org/downloads/motorcycle-rake-trail-calculator/

Racer/track guys adjust trail in 1/4" increments, or smaller...  Changing back to the stock tire size should slow down handling; I.e., a little more effort to get it started turning.  Think of reducing the trail as slightly negating the effects of gyroscopic action.

2.  Relative to rolling over/into things, Tony Foale
https://books.google.com/books?id=84hF-qoR5I8C&pg=PT90&lpg=PT90&dq=gyroscopic+larger+tire+size+motorcycle&source=web&ots=FYv2xIP8Mf&sig=mujCZQGyMvkBlyMXSIXFZj6uy4o&hl=en#v=onepage&q&f=false

has arguably the best treatise on bike handling ever done. From page 3-18:



Which also addresses the un-answered (but related) question of why dirt bikes have 21" front wheels...  That said, I am not sure how noticable this would be on our bikes...

3. Last (and probably most obvious) is the reduction in ground clearance with the smaller diameter tire.  Depending upon where and how you ride this may or may not be important.

Prolly more info than you wanted - but without a definitive answer   So.

I'd say that if the bike seems...skittish (or you just want it to handle slower), and/or you ride where there are numerous potholes that seem to affect the bike more than you think it should, and/or the bike bottoms out on speedbumps..., going back to the stock size tire would help all those maladies.  

[..]

So  I bought my Valk last year and just ran with the front tire that was on it without checking the tire size. It's time for a new tire so I started doing research. OEM size is 150/80 R17 but the tire on the bike is 150/60 R17, a full 2" smaller. I never had an issue riding but was wondering from the collective if there was an advantage (other than throwing off the speedometer) for having the smaller tire or should I return to the OEM size?

Did you check the back tire and the rear shock length.

Just wondering if the previous owner lowered everything?

[1NorthRyder]

I checked the rear tire and shocks and everything is stock so I ordered the OEM tire, went with the Metzler 880 as I could not find the correct size in the 888. They had one that was the right height but was a little narrower and I wasn't sure I would like that. Now I need to get an aluminum wheel polishing kit and shine those rims right up. Looks easy enough on the videos but I'm guessing it will be very time consuming.

[Tfrank59]

Polishing the rims does take a while but based on your location I think it'll be awhile before you can ride eh?

[1NorthRyder]

"Polishing the rims does take a while but based on your location I think it'll be awhile before you can ride eh?"

 Yup, I figure I have at least three months to polish them. I found what looks like a good wheel polishing kit and was going to pick it up on my way home from work today.

[Jess from VA]

I don't think any interstates came with polished and clear coated wheels.

Assuming they are cruddy like mine, always start out with the wheels by scrubbing the hell out of them with mildly corrosive spray-on wheel cleaner (or S100) and OOOO steel wool (and Nitrile gloves), followed by hot soapy water and stiff bristle brushes, and copious rinse and dry.  Only afterwards go to your good polishes (using a power drill with hard cotton 4-5" buffs; but avoid dragging the chuck on the aluminum wheels, that is really hard to buff out).

The front is easy, but the rear on an interstate is a sumbitch.  I use my lift, jack it up a little, and work from the rear on the part that is easy to reach (not pulling the bags to reach in from the sides); turning the wheel from time to time.

I even started the bike, put it in gear and let the rear spin while polishing (throttle lock at 1500rpm), but you can lose a finger or two if not really careful, and the wheel slots WILL stove your fingers.  But I did an hour of work this way that equaled about 4 hours the safe way.  And try not to breath too much exhaust in the process (choke).

Of course, taking the rear wheel off to polish it is the intelligent thing to do, but I am always wanting to get the new tire on and installed right away, and I'm not that intelligent (see paragraph 4).