Fat tyres - what are the benefits and short commings.

[pikipiki]

As the V9 bobber is shod in big rubber:
 Has anyone experience riding bike with this style of tyre? I assume the advantage is a slightly more comfortable ride, resistance to aquaplaning + less interfered with when riding over cats eyes and white lines + longer tyre life? but whats the down side? are these tyres all vague and I corners? how good a rider would you have to be to notice the inadequcies of this design?

[pete roper]

It's purely a styling excercise. There are no *engineering* benefits to such ridiculous cosmetic affectations.

Wheel and tyre sizes and profiles are always a compromise that is chosen with respect to function, frame geometry, weight bias, power etc. the *Ideals* for most conventional formats have long been established and have changed little over the last 15 years or more. The absurdity of the tyre choices for both of the V9 models speak volumes about the market that has been targeted, (And missed by a mile!) by the styling department who nowadays seem to run roughshod over the proto-engineers Noale seem to assign to Guzzi designs.

Pete

[Kev m]

I think trends in MC tire sizes have been largely driven by visual impact. And just like I think engine sizes are out of hand (I commented on a Harley forum tonight that Jenn and I have owned at least 4 cars with smaller engines than currently offered in Harley big twins), I also believe tire sizes have followed trend.

I find it funny that my 1996 RK had 130 series tires front and rear when now the standard rear for a Sportster is a 150. 😱

That said there are effects to size differences, especially if profiles and compounds remain essentially the same.

I went down from a 140 to a 130 on the rear of my Jackal and similarly down from a 150 to a 140 on the rear of my Sporty. Both times I would say I perceived lighter/quicker feels in the bike's handling. Mostly like it would fall in quicker and easier to the turn.

Granted, each time I was replacing a worn out tire so part of the feeling would be a natural improvement from the more rounded profile of the replacement, but still UNLESS each time I'm fooling myself I think something more was happening.

Ironically I went up in the front of the Sportster from a 100 to a 110 for a more planted feel and for perceived increase in contact patch.

Now I could be wrong or the theoretical benefits/costs might be negligible, but I think they may include:

* Fatter = fewer #of force/sq in. which may mean reduced wear/longer life, more grip in normal traction conditions, but potentially easier hydroplaning. The wider/fatter profile may slow down turn in or break over into corners and add some feel of increased stability.

Conversely

* Thinner = higher #of force/sq in. which can increase wear/shorten tire life, though if true may reduce ability to hydroplane (more force to push through to surface/displace water). The narrower profile lends a lighter feel that's quicker to turn in or break over.

Now these are generalizations and someone smarter than I may correct me if I'm mistaken in my physics theories.

I also realize there are other variables like tire pressures, compounds, differences in profiles and types (sport radials vs touring bias ply's).

Also it seems that dual compound tires are becoming popular (with harder compounds down the center for better highway wear and softer materials on the edges for better grip leaned over) which changes things up as well.

And truthfully, like so many things with our beloved obsession, we probably are making much ado over nothing.

But I'll continue to over think it anyway.

[Aaron D.]

It's more the match of front to rear that makes the bike feel good or un-good.

A new Scout flicks like a Morini 350 with low, fairly wide tires, and I suspect the V9 will do the same.

The practice is fro American bikes with rigid suspension-and the Scout has very little travel, so the sidewall is a welcome addition.

[Guzzistajohn]

For fat tires improved handling, Moto GP bikes would have them.

[Kev m]

For fat tires improved handling, Moto GP bikes would have them.

*If ?  Is that what you're saying?

I don't think anyone is claiming that fat tires improve handling.

But I think some might argue it can improve the performance of the tire/bike in certain categories/metrics while reducing performance in others.

Obviously Moto GP is a very narrow performance category.

[redrider]

"Mine are bigger than yours" is the undercurrent.

Really sad to hear the BS bandied about whenever there is a gathering of so called expert riders. Bike night, poker run/charity event.

I went "down" to a 180/55 from 190/50 on the Benelli. So much better when transitioning side to side. This is also a gnarly sport bike. I have no cruiser experience other than riding customer barges.

[charlie b]

Question.

Hydroplaning.  I had heard somewhere (at the time it seemed reliable, like a tire mfg site) that a motorcycle tire does not hydroplane until you reach triple digits.  Is this true at all?

[redrider]

Depends on several variables. The cause is water build up- the sipes can only channel so much. A worn tread hydroplanes at a much lower speed. A tire with many sipes planes at a higher speed. Torrential rain can overwhelm the best rain tire design. Recent motogp events seem to deal with it up to a point, then the red flag comes out.

I rode through 2" standing water during a toad strangler at 40mph with no difficulty. Avon Storm sport touring tire.

[Aaron D.]

For fat tires improved handling, Moto GP bikes would have them.

Funny-MotoGP tires are way fatter than my Scout's. Of course tire size is regulated there by rule.

[fotoguzzi]

Question.

Hydroplaning.  I had heard somewhere (at the time it seemed reliable, like a tire mfg site) that a motorcycle tire does not hydroplane until you reach triple digits.  Is this true at all?

try it, report back..

[Triple Jim]

I assume the advantage is a slightly more comfortable ride, resistance to aquaplaning...

I don't see how a larger tire would be less likely to hydroplane than a small one.  The big one has more area to trap water, and less force per unit area keeping it in contact with the road.  As mentioned above, motorcycles don't tend to have the problem as much as cars do, unless you're a Darksider with a flat profile car tire on the rear wheel.

[Toecutter]

For fat tires improved handling, Moto GP bikes would have them.

Umm... they run a 190 out back, and a 125 up front. That's pretty damn fat.

[pikipiki]

Umm... they run a 190 out back, and a 125 up front. That's pretty damn fat.

I dont think moto gp tyres can be compared they run sliks with around 2" less profile than the v9 bobber or HD fat bob.
regarding these bobber tyres Im not even sure if the tread pattern is a styling exercise? are they radials or bias ply? are there any benefits to these tyres.

I have Avon road rider bias ply on my v7 and on clean tarmac I have no issue with them although they dont much like white lines and round where I am there are a good few roads that have some loose chippings down the middle or on the ouside of curves and lots of these annoying warning stripes aproaching roundabouts we seem to have such a lot of in the uk. giving the benefit of the doubt id think that bobber might cope better with the white lines and warning stripes and I would think these tyres would last longer. Suzuki van van has a similar tyre on rear and aparently the milage on the tyres is 20k then again the van van is a different kind of bike, its cheap and simple the fat tyre makes up for primitve low rent suspension, its a 1970s throw back. I'm trying to find any justification for the 16" fat tyres but the more I think the more I agree it's just a styling exercise and not even one I like the style of....

[PJPR01]

V9 Bobber - city bike with fat tires...good for potholes.  Will be more comfortable than skinny tires.

[agoldfish]

Just my two cents based on years of biking, touring to track days.

Cosmetics / Visual impact / Styling aside, the narrowest tyre you can run without compromising grip will always be the best handling. As you have more power you need a larger contact patch to transfer that power to the ground.

My Ducati has a 170 on the rear, coming down from a 180, made it more flickable. And with only 80Bhp on tap a 180, and probably a 170, is overkill. My little V50 Monza has the skinny little 100 on the back and it is one of the best handling bikes i have ever riden. But with so little power its all it needs.

Have a look at the Moto3 Moto2 and MotoGP bikes, they are all race bikes achieving insane lean angles. There is about a  150Bhp disparity between a Moto3 bike and a MotoGP bike. One has skinny tyres, One has fat ones. Its about matching tyre size to the power, weight and application. Styling too, obviously.

Fatter tyres do aquaplane more easily than skinny ones. At the GP in Assen the MotoGP boys were complaing of Aquaplaning at 180mph down the long straight!!!! new underwear all round then!

Chris

[kirkemon]

The only possible benefit to those fat bobber tires is the contact patch where the rubber meets the road is larger. That may be better in a panic stop (?)
My experience is that fatter tires slow the steering.
But I agree that it is purely a visual thing - are white walls next?   

[ITSec]

Question.

Hydroplaning.  I had heard somewhere (at the time it seemed reliable, like a tire mfg site) that a motorcycle tire does not hydroplane until you reach triple digits.  Is this true at all?

I can state without any question that a motorcycle can hydroplane at much lower than 3-digit speeds - from personal experience. Fortunately, I managed to gather things up before something awful happened.

And from an earlier comment/question, a narrower tire will hydroplane LESS easily than a wide one. The trade-off for a smaller contact patch is that it will have greater force pushing the tire down through the water into contact with the road. Now, as to whether that contact has good friction or is greasy? Another matter...

Tire size and proportion are all a matter of complementing two things - the mechanical design of the bike and its suspension, and the cosmetic aesthetic of the bike. This is also true of cars and non-commercial trucks. Sport bikes have fat rear tires and relatively narrow front ones; standards used to have (and some still do) tires that are close in size at each end. Adventure bikes go from a sport-bike like configuration for the more street oriented ones to a narrow rear with a super-skinny front  for the more dirt-oriented ones. There are reasons for all these changes.

[Guzzistajohn]

*If ?  Is that what you're saying?

I don't think anyone is claiming that fat tires improve handling.

But I think some might argue it can improve the performance of the tire/bike in certain categories/metrics while reducing performance in others.

Obviously Moto GP is a very narrow performance category.

Yes I meant "if" that was pre am coffee. And yes, it depends on the performance you're looking for.

[Arizona Wayne]

Fat/bobber front tires weigh more so effect the handling of your steering.  It's like you have a flywheel on the front rim and you can't ignore it.  With a front end like that there's no way you are going to be able to haul ass thru a corner like I can on my MuZ 660 single w/a 110/70-17 front tire.   

[LowRyter]

fat tires slow the steering and make the bike less flick-able.

[PJPR01]

Fat tire designed for potholes and cobblestones...not necessarily for racing.  Good For Chicago and Houston streets for sure...

[Tom]

As state by others already.  Bigger tires mostly for styling.  Good - larger contact patch for braking.  Bad - cost more.  Less efficient because of larger contact.  More to push down the road.

[oldbike54]

Fat tire designed for potholes and cobblestones...not necessarily for racing.  Good
For Chicago and Houston streets for sure...

 Here is what I think I know , please feel free to correct .

 Comparing race tires and race bike geometry to street tires and most street bike geometry is coconuts to tornadoes . Race tires have a different profile designed to allow for quick roll in, so the enormous sizes don't react the same as most really wide street tires . Additionally ,pavement race bikes run really steep steering angles and very little trail and require a higher level of effort and concentration than is acceptable to most street riders . The level of traction available from true race tires is incredible , which when dealing with 240 HP is kind of important .

 Dusty

[charlie b]

I can state without any question that a motorcycle can hydroplane at much lower than 3-digit speeds - from personal experience. Fortunately, I managed to gather things up before something awful happened.

So what were the circumstances.

I know I've traveled down the flooded 'rut' on an interstate at around 70mph without any issues.  I am more afraid of painted white stripes or intersections.

[ITSec]

So what were the circumstances.

I know I've traveled down the flooded 'rut' on an interstate at around 70mph without any issues.  I am more afraid of painted white stripes or intersections.

I was traveling about 50-60 mph or so, had a front tire at about 40-50% wear, and went through a fairly large pond that had developed during/after a rainstorm. That particular tire design (I later decided) did not have especially good siping or channels to draw water away from the center. About 1/3rd of the way into the standing water, the front began to get that wonderful floaty feeling that tells you it isn't touching the pavement any more. It is a different feel from the tire sliding.

On the PR4s and tires with similar treads, I've never experienced this, but they have much better designs for wet riding.

[rboe]

Stock Metzlers on the Griso, hydroplaned on I-17 north of Camp Verde in the left lane at around 70 during a gully washer. Scared the #$%* out of me. Fairly new tire too.

[Fuzzy]

Big tires make me feel stable and happy. I would love to be able to use them. If anyone has a 400 lb bike with a saddle height about 31" that uses such ridiculous tires, maybe we could work a trade for my Breva.

[ITSec]

Big tires make me feel stable and happy. I would love to be able to use them. If anyone has a 400 lb bike with a saddle height about 31" that uses such ridiculous tires, maybe we could work a trade for my Breva.

I wish it would only take big tires to make me feel stable and happy - I gave up on that long ago! 

[Arizona Wayne]

Your tire size preference depends on your riding style preference.  If you want stability no matter what and speed thru corners is not what you care about, then fat tires front & rear are for you.