bigger tires on a 600 monster

[QueenBee]

hey guys!
Can u help with this
Can i put bigger tires on a ducati monster 600?
Front wheel -i have 120/60/17  and i would like to change it with 120/70/17
Back wheel- i have 160/60/17 and i would like to change it with 180/55/17
or tell me about the sizes that fit my ducati. 

I just bought motorcycle and i don't know so many things about it!
anyway, looking forward for an answer
thanks!

[Slide Panda]

For the front, you might get away with the 120/70/17s - that's what a same year 900 runs.  But it will make your front end a bit higher due to the taller side wall of the 70.  That 2nd number (70) is the side wall height ratio to the width of the tire - so your side wall would be .70(the ratio)*120(the width) vs .60*120 on your current tires.  A taller front tire would effectively change your rake, increasing it.  The larger the rake angle, the greater straight stability a bike will tend towards, at the cost of quicker turning in.  So I'd stick with the 120/60/17


For the rear - don't.  You cannot mount that big a tire on your stock rims, just won't fit.  So if you really wanted to do it, you've be looking at a lot of work and cost to fit up a different wheel, that would ultimately lead to a poorer preforming bike.  You'd end up with a heavier wheel assembly, so you'd be adding weight to one of the worst spots on the bike.  It takes a lot of force to get a mass spinning or get it to stop.  So more weight = slower accel and decel.  Also, when you're initiating a turn it would require more from you to over come the greater gyro mass of the bigger wheel/tire. 


A 600 doesn't have enough brute force to warrant a bigger tire.. hell a 900 probably doesn't need the 180s that they run. 

Here's a link to some details on tires
http://ducatimonsterforum.org/index.php?topic=20996.0

[QueenBee]

so, you are saying that i should get the  120/70/17 s  instead of the ones from stock?120/60/17.
This will increase my stability...this is what i understood from what you told me .

[the_Journeyman]

I know on my 1999 M750 the 120/70 works just fine, gives you a bit more cushion on bumps etc.  As mentioned, you will ride a bit higher which can be compensated for by raising the rear or letting the forks ride a bit higher in the tree.  You will gain nothing but slower tip-in from the 180 rear.  It won't fit through.  A 170 *might* fit, but I don't know and it will still slow your tip-in down.

JM

[Slide Panda]

so, you are saying that i should get the  120/70/17 s  instead of the ones from stock?120/60/17.
This will increase my stability...this is what i understood from what you told me .

I noticed I made a typo at the end of the front tire note - I meant I'd stick with 120/60.  More stability also means more effort to tip in.  Like JM said, 120/70 will work, but there's no real reason to.  Also 120/70 will weigh more than a 120/60 - as before more weight is not what you want. 

[QueenBee]

thanks for the answers .
i still don't know what to do.
the thing is that,  i bought without realising 120/70; this is the reason why i was asking.
i don't really care about the speed performonance; i just don't want anything to happen when riding(i don't know if "ridding "" is the correct word  ).
like i said, i just got my licence and right now all i care about is my personal safety.... not speed
take care! 

[Slide Panda]

Heh - I didn't mean to come off as a speed freak.. Just trying to illuminate the repercussions of adding weight to the wheels... I didn't even get started on sprung vs un-sprung weight.  I was just trying to point out that  adding weight will negatively effect a number of  characteristics.

For your current tire situation, you'll be fine with a 120/70 up front.  If it's not easy/cost free for you to swap it for a 120/60, then just use the 120/70. 

Enjoy the bike - you just opened a can of technical worms with your question.

[OT]

Your stability (which is what it sounds like you're asking) has far more to do with the weight of the wheels (not the tires alone) and the speed of the bike.  The faster you go the harder it is to get the bike to tip over into a turn (remember, you have to tip the bike to lean and turn it), and the heavier the wheels (stock wheels are usually the heaviest) the harder it is to get the bike to tip over - that's because heavy wheels turning fast want to keep turning and the bike wants to keep rolling - even if you fell off the bike would keep going upright and straight ahead until it hit something.  You'll never see a motorcycle racer crash on a straightaway, even when going 200 mph....unless something breaks or someone hits her/him (queue Sete Gibernau).

You want to make sure you aren't going too slowly or slowing down when turning cause that'll make the bike feel like it's falling over (and triggering a reaction to slow more, which makes the feeling worse - you get the picture).

The tire ratios aren't the whole story, either.  Over the past several years tire profiles (when viewed straight on) have been modified to enable quicker tipping and give more grip when leaned way over.  These types of tires have more of a V-shaped profile (but it's really subtle), so make sure about the tire's profile when you specify a ratio to the salesperson - you don't want the v-shaped ones....

IMO, it sounds like you'd be far better off to spend that tire money on good riding classes, like at California Superbike School (CSS/Keith Code), where you'll learn to understand and feel what makes your bike ride like it does, or even the Motorcycle Safety Foundation (MSF) if you're uncomfortable on the street with all the traffic around you.

Check out Proficient Motorcycling & More Proficient Motorcycling by Hough - they're a good read and very informative