Some thoughts on tires

[jimp]

I'm on my 4th set of tires and a recent ride got me to thinking about my current set, so I thought I'd review what I've done so far....  Keep in mind I am in California and our roads may not be like yours. I'm surrounded by mountains, and have even better mountain roads within a few hours ride. Also, California roads are crap - the cities, counties (some) and state are having a hard time finding the money to repair them. I should mention that I am a Michelin fanboy - I've been using them since the late 80's on my Connie's. Tried other tires, but always come back to Michelin.

The original BT021's were interesting. At higher speeds the front wanted to run wide in a turn and took more effort to turn. Somewhat disconcerting, but never a problem once you got used to it. But I loved them at low speed. I'm talking less then 30mph. The front was extremely fast responding to input. Lane splitting was like dancing - you could go were you thought.

I replaced them with Michelin PR's in OEM size (this is before the PR2). I noticed an immediate improvement in high speed handling. Roll-ins to curves were more predictable and stable. No tendency to run wide, fall in, or other such nonsense. And the rear just stuck. But lane splitting became harder - it took more effort to move the front tire and go where you wanted.

After the PR's wore out, I went with PR2's with a 180/50 rear thinking it would help quicken the steering. That it did, but at the expense of rear end grip. Every so often, charging a tight corner in the mountains, the rear tire would slip just ever so slightly. Never a problem, but enough to get your attention. And that smaller rear didn't help with lane splitting. The front still took more effort to turn at low speed.

So now I'm on the PR2 with a 190/55 rear. While this doesn't have the rear end slipping like the 180, it's affect on the steering has got me thinking that, with Michelin tires at least, the OEM size is best. Like the 180, the 190/55 quickened the steering, but to the point where the front now wants to let go before the rear. On the other hand, lane splitting has gotten easier with quicker response.

What does this mean to you? I have no idea. But of the choices, it seems for me that the Michelins OEM size works best for mountain riding, and I'll deal with the slower lane splitting response.

Just some thoughts on the tires I've run....

 

[Gypsy JR]

I have not tried anything but OEM sizes on mine. 120/70 and 190/50, first PR2s and now PR3s.

I really can't report anything about them, they never intruded on my riding. I think that is good?  :motonoises:

 

[Fred H.]

I typically don't like to stray from the OEM tire sizes on bikes. When you do, it always helps one aspect of handling but hurts another. The manufacture goes to a lot of trouble doing testing at just about all attainable speeds and has selected the tire size that works best with the bike in all situations. They also work closely with the tire manufactures in choosing the tire size and construction type that will work best with the bike. Metzler even takes various model bikes out on the Autobahn and runs them two-up as fast as they can go looking for any abnormal behavior during their homologation testing.

I hear from lots of folks who have tried other tire sizes on different bikes, and the story is always the same. It helped one aspect but hurt several others, and most of them come back to the OEM tire sizes after running a few sets of the off size, and find that overall the OEM size does indeed work better overall.

 

[jimp]

Been thinking about this some more....  The OEM size PR's were heavy steering in the tight twisties of the Santa Cruz Mtns, but were great on the more open curves in the Sierras and Rockies. Since most of my riding is in the local mountains, with their narrow, twisty roads, I wanted to quicken the steering, because on the OEM size I was wore out after my 100 mile Sunday morning loop pushing the front end through endless turn after turn.

After my experience with the different rear tires, I have to agree with Fred, the OEM size seems to be the best for the C14. Unlike the '94 and up C10 which worked better when you swapped the 120/70 front for a 110/80. But on the 14, I wouldn't want to do that - it wouldn't work with the wider rear, and the wider front rim.

Maybe I'll have to give up my beloved Michelins and switch to a different brand to get the handling I'm looking for.

 

[Fred H.]

Even within a specific size, you'll find differences in the profile of motorcycle tires that will impact the lean in characteristics. I think both the Bridgestones and Pirelli Angel's have a quicker feel to them than the Michelins do. Though most don't care for the bad wear characteristics of the Bridgestones.

Personally, I'm happy with the way the PR3's handle. But my other bike is a GoldWing, so my definition of "flickable" may be different than someone coming off a sport bike.

 

[rcannon409]

Tires are very difficult to evaluate and compare.  For example, Honda oem tires have to meet specific curb impact tests and are not like the aftermarket tire it will be replaced with...even though the two may appear identical, right down to model numbers and markings.  Its laos a HUGE deal if a factory can save 15 cents per tire, or 1/4 lb of weight. They are also not opposed to dropping any tire package that will fit if the price is right and the specs are within range.  I remember the  2004 Yamaha yz250 stopped putting a white background on their front numberplate to save 3 cents per bike.  They were trying to avoid a price increase, and this change helped them meat the goal.  Dollars saved on a  tire might get  a guy a huge promotion.

Also, a new pr2 had fairly deep tread on the tire.  There will be  a difference in circumference, and height,  in a new tire vs one with 7000 miles on it.  Not to mention the size standard which does not really exist, at least down to the mm.  A worn pr2 vs a new one will show the old one to be about 10mm less in height due to missing rubber. 

The stock bike pushes wide in turns and this is easy to deal with. A 190/55 tire, or some extra rear preload (or less front) stops this.  But, raising the rear with preload changes suspension and handling. Raising it with tire size does not change the rear suspension action to any real degree, but will change geometry.  If preload and sag settings end up in the "good" range with a 190/55 tire, your bike will handle slightly quicker vs the 190/50. But if a tire size change requires excessive, or too little preload, the bike will handle odd.  Its best to have th e sag, front and rear, set properly, then to play with tire size for the finishing touch.

Thats all the options we have on a stock bike.

Freds new Ohlins will offer high speed compression, and probably shock length change as a way to change things.  High speed compression adjustments tend to effect rear ride height...odd, but true.

But, if  a person adds this taller rear tire, without other measurements, theres no tellign what they might end up with in regards to handling.