tire width question

[lee_harvey]

being a convert from the japanese side of things i think a wider rear tire (not excessive, 5-15mm or so)would be a good thing, better grip, increased lean, etc. But after talking to Bruce of boxers by bruce, he said that it would negatively affect my handleing.?? so my question is, how many of you are running stock tire size and if you have ever increased the width, and to what result. The tiny stock tires just dont instill alot of confidence with me.

[Mike V]

Lee,

Don't do it (my personal opinion). I've never heard of this procedure to be beneficial in improving grip or handling. A wider tire will most likely make the bike want to stay in a vertical or upright profile instead of ease in direction change. You would have to almost double the tire width to improve on the actual contact patch area which is pretty close to the size of a quarter. There's also swingarm and other clearance issues to deal with in a wider tire and structural integrity issues with wheel bearings that may be pushing the envelope. Your wheels are designed and engineered for a specific tire fitment. This is a pretty common topic to those new to these bikes. I've learned over the years there's a specific reason for the dimensions and aspect ratios on these bikes - they work best as is. Aesthetically it may be an enhancement based on personal opinion. But a wider tire may only result in a domino effect of more problems and expendatures. In my opinion. I'm interested to hear the opinions of the others on the list...

[Bob_Roller]

The widest rear tire you can put on a twin shock R65, is a 120 metric size .

[Semper Gumby]

Hi Lee,

I have experimented with larger sizes front tires and rear tires.

As far as the rear tires the stock size is 4.00-18.  The only oversize that usually works is the 120/90-18.  There are no handling benefits in using this oversize.  Depending on brand the tire may rub on the RH side of the swing-arm.  This size also must be completely deflated in order to remove from or put on the bike.  If you must have a particular brand of 120/90-18 that does rub there are rumors of spacers (Boxerworks?) that can be installed between the final drive and the rear wheel that will move the tire away from the swing arm.

As a result I am sticking with the 4.00-18 rear.  I think the handling is better and I have ridden clear across the country and plowed around the North Georgia mountains at speed.  The tire looks small but do not worry.  It will keep you butt firmly on the road.  Worry more about the quality of 4.00-18 tire.  I recommend the highest quality of tire: to include the Bridgestone, the Metzler, and my favorite the Michelin.  The Michelin Macadams are going away so I am about to try my first soon to be available Michelin Pilot Activ in the 4.00H18 size.

As far as front tires are concerned.  You can't get 3.25-18 tires anymore - they don't exist in a quality brand (see above).  The 90/90-18 is actually a little undersized the 3.25-18 and the 100/90-18 is over-sized.

If you have a naked R65 either the 90/90-18 or the 100/90-18 will work in a quality brand.   If you have a highly modified R65 with Fairing / bags / top-case you can if you want put a 110/90-18 rear tire on the front (turned around) to account for the increased weight of the bike over stock.  The fender mount will have to be modified to allow for the increased diameter.  And the handling will be very different.  It will be much more stable (it want to stand up.)  And it will not change directions as fast as the front tires.  But you will be able to safely carry the extra weight.

[Semper Gumby]

Also Lee,

I just got about 16,000 miles out of a Avon Roadrunner 4.00H18. Before that I got about 20,000 miles out of a Michelin Macadam 120/90H18.  

Michelin advertises that the Pilot Activ will last 20% longer (than the Macadam).  We will see.

PS - ADD AVON Road Runners to the list of "Quality Brands" from previous post.  I thought the Macadam was better in the wet than the Avon.  The Avon roadrunners on my BSA Firebird and Honda CBR600F seem squirmy.  I am looking forward to trying the Pilot Activ.

The best tires I ever had on a bike were the Metzler ME33/ME-1 Comp K (Dot legal race tires).  The CBR 600F would lean at unbelievable angles on these tires after they warmed up.  Unfortunately they lasted about 3,000 miles and aren't available anymore.  Todays Metzler's seem too hard for my liking.

Your result may vary.

Caveat Emptor.

[montmil]

The tiny stock tires just dont instill alot of confidence with me.

Define "tiny".

A 120 section is the most you can stuff between the swingarm, well, arms. I know. I yanked a rubbin' 120 and went back to 110's on both my R65s.

Doubt if BMW Motorrad ever envisioned the R65 as a cafe racer or a racer of any disicpline. Not designed as a racer so I wouldn't expect it to morph into a real race bike.

Monte

[lee_harvey]

thanks for the responses guys, looks like im gonna stick with stock size but just in a quality tire.
montmil- by tiny i mean this, on my ninja i had a 160/17, and went up to a 180/17. 100/90 seems quite small by comparison. but then again, different bike, different set up and purpose.
im not looking to turn it into a crazy race machine, speed is not my goal. If i wanted that i would get another ninja. i just want something that is decidedly different from what you normally see, a little more style if you will. but i do LOVE attacking corners, hence my concern about tires.
semper- i had michelin pilots on the ninja and loved them, but they didnt seem to last too long, then again, i put a little over 10k miles on them in less than a year.

[GrimReaper]

Bigger tire does not mean better handling.I have a lot stunt rider friends and most of them prefer smaller rear tire for better handling

[GrimReaper]

Just took a look at my wheels.Both rims are the same size 2.50.Front tire 90/90(guess i can go bigger since i want to put windscreen)Rear 120/90 no problem at all

[nhmaf]

Even with the "tiny" 110/90 rear and 100/90 front on Tillie, I was able to drag the centerstand bits various times in the mountains of west virginia going around corners with 80 lbs of soft luggage on the back.  With decent tires on these bikes, you'll be grinding hardware before you run out of rubber.  Many(but not all) of the 120/90 rears will cause rubbing unless inflated to crazy pressures, and the hassles of removal outweigh any possible benefit, IMHO.

[Semper Gumby]

Hi Lee,

The Pilot Activ/Macadam should wear a lot longer than the Pilot Sport tires you were using on the Ninja (?) as they are more of a touring tire.