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Recently watched "Can I get More GRIP from a Wider Motorcycle Tyre?"

Afan

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Recently watched this video clip, "Can I get More GRIP from a Wider Motorcycle Tyre?". What's your thought on this matter?

[video=youtube_share;Le54XI9mMcI]https://youtu.be/Le54XI9mMcI[/video]
 
My thoughts are that I don’t have enough experience and knowledge of the characteristics of different tire sizes on a motorcycle to make a judgement. I don’t think the author of this video does either. Therefore I’m going to stay with the tire size Honda recommended, on the assumption that they know more about tires than I do. The stock sizes work fine, and they are safe to ride on. Until they don’t/aren’t, I see no reason to change.
my interpretation of this is that it was looking at a 150 vs a 170 when the stock 160 isn't available in the type of tire you want

there aren't many 80/20 160s available
 
my interpretation of this is that it was looking at a 150 vs a 170 when the stock 160 isn't available in the type of tire you want

there aren't many 80/20 160s available

Good point. I didn’t pay enough attention as to why the author was considering a wider tire in the first place.
 
my interpretation of this is that it was looking at a 150 vs a 170 when the stock 160 isn't available in the type of tire you want

there aren't many 80/20 160s available

That's how I understood the video too.
And, as an example, so often on this forum: Shinko 705.
 
Grip (traction) is primarily a function of weight, so _assuming_ both those sizes list our rims as appropriate and acceptable width, I don’t think it’ll make much difference in grip at all. I’d expect handling feel to be different.
 
Wider Tire..........

afan,

Does it also unintentionally imply at the end that the wider tire is lower in height, and by inference, maybe an alternate choice for those of us who are shorter?


Slo_Rider
 
The best handling bike I even had was without a doubt a Ducati. Now the NC is no Duc, it was never meant to be. But the stock NC with stock tires is awful damn good. It will lean much further over, holding firm than most riders are willing or capable of pursuing.

Honda knows what they are doing when they screw together a motorcycle. Have for a long time. And they have done it more than anyone else at anytime ever.
 
I agree with the assessment on the video for the reasons outlined. Fitting a larger profile tyre to the same rim has always been pointless on the road at least.
 
The formula for friction is
Friction=uN
u is the coeficient of friction
N is the normal force (weight pushing down)

Area plays no part what so ever. Don't worry about the width, physics is physics
 
afan,

Does it also unintentionally imply at the end that the wider tire is lower in height, and by inference, maybe an alternate choice for those of us who are shorter?


Slo_Rider
comparing a 150/70 and a 170/60, the former should be 25.3" tall and the latter 24.6" tall, so you'd lower the rear of the bike about 3/8" using the 150/70 rather than the 170/60, if both tires are true to size on the NC wheel (I don't know if they are).
The formula for friction is
Friction=uN
u is the coeficient of friction
N is the normal force (weight pushing down)

Area plays no part what so ever. Don't worry about the width, physics is physics
that's a basic formula that gets used, but in reality there are other factors that matter

they mostly play a role in determining u, so I'm not saying the formula is wrong, but if you think that contact patch size and shape don't matter you're mistaken.
 
afan,
Does it also unintentionally imply at the end that the wider tire is lower in height, and by inference, maybe an alternate choice for those of us who are shorter?
Slo_Rider

I will not use the video, but rather from my own experience, on my ST1100 I had PR4 "size smaller" (don't remember the numbers right now, but there wasn't PR4 in "original" ST size) and it did lower the bike a bit so I was able to flatfoot. It lowered so much that original kickstand made ST more upright so I had to replace with shorter version of the kickstand.

In NC case I'll probably go in opposite direction and make the bike/ground clearance a bit higher because I plan to do some easy off-road riding.
 
You really have to run the numbers to figure out if it'll raise or lower the bike

the first two numbers of tire size are width and profile (height as % of width), the third is wheel diameter

multiply the first by the second, divide by 100, and you have the tire height (above the wheel) in mm

for example, stock NC is 160/60 so 160 x 60/100 = 96mm

a 150/70 should be 105mm, so it'll raise the bike 9mm

a 170/60 should be 102mm, so it'll raise the bike 6mm

it appears that the ST1100 calls for a 160/70-17 rear, which is unusual by modern standards. It would be 112mm above the wheel. If you swapped for the 160/60 that's more common today, that would lower the rear of the bike by 16mm, even though the tire is the same width.

Of course, all of this is assuming that tires run true to size. They often don't.
 
... it appears that the ST1100 calls for a 160/70-17 rear, which is unusual by modern standards. It would be 112mm above the wheel. If you swapped for the 160/60 that's more common today, that would lower the rear of the bike by 16mm, even though the tire is the same width...
Exactly, instead 160/70 I installed 160/60 and it lowered the bike. I talked about the hight, not width of the tire - what Slo_Rider was asking.
 
I'm not saying the formula is wrong, but if you think that contact patch size and shape don't matter you're mistaken.

100% fact. While it may not be advantageous to put a wider tire on the stock width NC rim, a wider tire on a wider rim (like a 190 rear on a 6" rim) will 100% give you much more grip, due to increased contact patch. The issue at hand is putting a wider tire on the stock NC rim, distorting it's shape, which skews end results. There is a reason 180-200hp literbikes come with 190 rear tires and 50-55hp NC's come with 160's.....

Using the argument of friction and weight does not take into consideration the increase of contact patch in this application. That's like saying running 10.5" wide street car slicks on John Force's funny car would work just as good..

There's also the theory of a wider tire providing more lean angle, because the edges of the tire is wider, therefore being closer to the outside edges of the bike. Picture 2 identical bikes sitting side by side and you are viewing them from the back. One has a 190mm rear tire, the other has a 160mm rear, both sizes on width-correct wheels. Draw a line from the edges of both rear tires up to the ends of the footpegs (usually first thing that scrubs when leaned), that will provide geometric visuals for the different lean angles, as the bike with the 190mm rear tire can lean a bit farther before the footpeg touches down than the bike with the 160mm.
 
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100% fact. While it may not be advantageous to put a wider tire on the stock width NC rim, a wider tire on a wider rim (like a 190 rear on a 6" rim) will 100% give you much more grip, due to increased contact patch. The issue at hand is putting a wider tire on the stock NC rim, distorting it's shape, which skews end results. There is a reason 180-200hp literbikes come with 190 rear tires and 50-55hp NC's come with 160's.....

Using the argument of friction and weight does not take into consideration the increase of contact patch in this application. That's like saying running 10.5" wide street car slicks on John Force's funny car would work just as good..

There's also the theory of a wider tire providing more lean angle, because the edges of the tire is wider, therefore being closer to the outside edges of the bike. Picture 2 identical bikes sitting side by side and you are viewing them from the back. One has a 190mm rear tire, the other has a 160mm rear, both sizes on width-correct wheels. Draw a line from the edges of both rear tires up to the ends of the footpegs (usually first thing that scrubs when leaned), that will provide geometric visuals for the different lean angles, as the bike with the 190mm rear tire can lean a bit farther before the footpeg touches down than the bike with the 160mm.

The advantage of increased tire width in performance applications has absolutely nothing to do with the size of the contact patch. It has to do with heat management. Physics doesn't change because it's a tire.

By increasing the width of the tire, you increase the contact patch, but that does not alter the friction equation. What you're doing is increasing the size of the area not in contact with the asphalt. Traction is lost because the coefficient of friction at the contact patch drops when the temperature rises too high. The increased area not in contact with the road allows for a greater amount of heat transfer from the tire to the air. By increasing cooling, it allows for the normal force to increase without overheating the tire and dropping the coefficient of friction.

Your increased traction has nothing to do with the area of the contact patch. The increase in contact patch is incidental the process.
 
Basically that's a fancy way of saying a larger contact patch creates conditions that manages heat more efficiently, thus increasing grip and tire wear, as heat cycling also wears tires faster.

Sent from my SM-G930V using Tapatalk
 
Basically that's a fancy way of saying a larger contact patch creates conditions that manages heat more efficiently, thus increasing grip and tire wear, as heat cycling also wears tires faster.

Sent from my SM-G930V using Tapatalk

No, that's a fancy way of saying that contact patch makes no difference at all. None. Contact patch size is incidental to the effect. The area of the surface in contact with the asphalt has no effect on the friction force. The friction equation is settled. 1st semester physics. Area is not in that equation.
 
Slightly wider tires don’t make a larger contact patch, they make a wider but shorter one. Deflating the tire slightly makes a _larger_ contact patch, because you reduce the psi of the patch, thus a larger patch is required to hold you off the ground.
 
except that tires aren't balloons: they have carcass rigidity, pressure isn't constant (tire pressure) across the patch.
 
You're welcome to go let air out of a tire and watch this miraculous phenomenon for yourself. (-;

What I have described (in both posts in this thread) is well known and well demonstrated in tires, both on-road and off-.
 
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