Does the width of rear tyre affect stability of motorcycle?

[The_Big_K]

That's my question to all great automobile/mechanical engineers out there!

The question popped up in my mind after watching the Yamaha R15 - the bike with stunning looks and a thin rear tyre .

Does it affect the stability of the mobike at higher speeds?

[raj87verma88]

Frankly speaking Biggie, the R 15 is a joke. It would have been acceptable if the price range had been around Rs. 50,000 to 60,000 but a price tag of over 1,00,000 is too much to digest. If the bike had been a 250 cc then it would have been OK but for a 150 cc. Now coming to the point i.e. tyre. Its a pencil tyre. Yes, the size of the tire does effect the performance. The World Wide Web has forums and sites full of debates on this subject. I am posting some links for your reference.
Front Tire Skinny vs Fat tire - TWT Forums
Mazda6Tech - Are Wider Tires Better?
What's the largest size tire I can fit in my Xterra? - Automotive Forums .com Car Chat
Will post more later.

[The_Big_K]

Hey, thanks patty! You are no doubt well informed about bikes. Thanks for the links. Looks like there' lot to read!

[just2rock]

Yes thats all true,patty .The bike looks awsome..crazy bike look will attract all and so will they pay also,as you seen in Karisma.But yes those who will think on the design specifications will definately stop before

[gohm]

Yes, the thinner the tire the smaller the possible contact patch. This leads to a less stabile tire that also cannot put power down to the pavement effectively. Conversely though, it can turn in quicker so improved handling.

[sonasathish]

i don know what you guys are trying to explain! Do you think that the engineers who designed this bike never had a thought about your point! Sounds crazy

[ash]

Don't forget having a thinner profile decreases the drag coefficient too!

I think so, anyway

[raj87verma88]

Originally Posted by sonasathish

i don know what you guys are trying to explain! Do you think that the engineers who designed this bike never had a thought about your point! Sounds crazy

The simple truth is that a fatter tyre will provided better stability and balance and a thinner tyre better acceleration and mileage, but the tyre used in the motorcycles available in India are too thin. It is as if the companies are more concerned about their profits than anything else. And now tell me, if the thinner tyre had the same level of stability as a fat one, won't they put it on a superbike rather than those huge 200mm tyres.
I will take an example of Hero Honda Karizma, the first generation Karizma was 225cc and had the best acceleration among all bikes in India. The next generation Krizma R had the same engine but an even quickr acceleration. There must have been modifications in the engine but the thing that is to be noted is that the tyre was now thinner than the previos version's. Speed thrills and that is why these bikes are making business and also give decent mileage. Frankly speaking the companies are more concerned about their profit, sales than the safety of the riders.
A good example of a bike that had a mindblowing acceleration, good top speed, solid handling and had a not a very big tyre but a decent size is the RD series from Yamaha. RD 350 was availble here but was later banned as it was a 2 stroke.

Originally Posted by ash

Don't forget having a thinner profile decreases the drag coefficient too!

I think so, anyway

I think it should

[The_Big_K]

Originally Posted by sonasathish

i don know what you guys are trying to explain! Do you think that the engineers who designed this bike never had a thought about your point! Sounds crazy

Yes, they must have thought of it. But you see, understanding why they did it and what they missed - could lead to new ideas & development.

[gohm]

Yep, it is a marketable product designed to fit a niche of the manufacture and be profitable. Hence there is always room for improvement and customization to taste or usage.

[mayurpathak]

Guys, do you remember Naoya Kaneko's (Kawasaki) interview? He said they first decide the size of tyres before they design a bike.

Fatter tyre is used when you have a bigger engine, since you need more stability. Otherwise the vehicle will lose ground contact. Thinner tyres, however doesn't allow the bike to cruise at higher speed too much. Its difficult to turn the bike at a high speed with thinner tyres. But they are good for off the road biking, unlike SUV's where thicker tyres are used when the vehicles have to go off the road

[raj87verma88]

Originally Posted by mayurpathak

Guys, do you remember Naoya Kaneko's (Kawasaki) interview? He said they first decide the size of tyres before they design a bike.

Fatter tyre is used when you have a bigger engine, since you need more stability. Otherwise the vehicle will lose ground contact. Thinner tyres, however doesn't allow the bike to cruise at higher speed too much. Its difficult to turn the bike at a high speed with thinner tyres. But they are good for off the road biking, unlike SUV's where thicker tyres are used when the vehicles have to go off the road

You can modify your bike later. I have a Royal Enfield which comes with a 130mm tyre, I got a 160mm fitted on it. The engine feels no load, it is running as smoothly as before and there is no sufficient dip in mileage.
I agree with what Mr. Kaneko said, also he his far more experienced but we should remember that for the race track you have to be accurate. You can not have a slightly thin or slightly thick tyre there. But on road you can modify.

[gohm]

Actually it is easier to turn a bike with thinner tires at high speed. Less friction and mass to hinder the re-direction of the gyroscopic forces that cause the bike to lean.