Darksiders

With many GoldWing tires lasting just 10,000 miles compared to the 30,000 or more from automotive tires that cost half as much to begin with, plus some additional fuel mileage, the economics of it make obvious sense. Wet-weather traction is also greatly improved, according to the reports of many Darksiders.

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StoneFree said:

Tire manufacturers design tires for specific applications and I would not use a tire that isn't designed for motorcycles on a motorcycle for everyday use. It might work for a show bike but for everyday riding I want a tire designed for that purpose.


By way of example a car tire is not designed to ride on it's edge but a motorcycle tire is designed to do that.

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StoneFree said:

Tire manufacturers design tires for specific applications and I would not use a tire that isn't designed for motorcycles on a motorcycle for everyday use. It might work for a show bike but for everyday riding I want a tire designed for that purpose.


By way of example a car tire is not designed to ride on it's edge but a motorcycle tire is designed to do that.

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Testiphony said:

I completely agree with you. I think that you should use tires that are made for motorcycles on motorcycles.

Is there any risk of warranty of insurance being affected because you are using improper tires?

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Livin On said:

Indeed, but it seems most of the guys doing this aren't chasing chicken strips anyways. Whens the last time you saw a big bagger over on its edges 0

The justification seems to be most miles are being layed down in flat steady state conditions...

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StoneFree said:

The last group ride I went on had three Harley cruises end up off the road. It happens more often than people seem to know.


There is absolutely no advantage to a car tire on long highway runs. Yes, a car tire will probably wear longer because they're made from a much harder compound but with that comes a lack of road adhesion that is critical for a motorcycle.


Simple conclusion. People that do this are stupid IMHO.

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Livin On said:

Hey wondering if anyone here knows anyone who Darksides? For those who don't know Darksiding is the practice of riding with car tires on the bike (usually in the rear), its popular with tourers, mainly goldwingers. Supposedly they see increased tire longevity as well as better wet weather traction...

Tales From the Dark Side: Putting Car Tires on Motorcycles | Rider Magazine
No Fixed Abode: The dark side of unintended consequences. | The Truth About Cars

Going to the Darkside with a KUMHO RF on a GL1800 Goldwing - YouTube

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Spock001 said:

I'm a dark sider. I wouldn't consider it for my Street, though. Yes mileage can be quadrupled. For big cruising bikes just under inflate to the "sweet spot pressure."

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StoneFree said:

Just remember that what you're doing is very unsafe because automotive tires are not designed to used on motorcycles and that you've also quadrupled the likelihood of killing yourself, or worse still, an innocent passenger on your motorcycle.

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harleyhoonigan said:

Good point on safety, i guess if it really did work out well it would have already been done on a much larger scale.

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StoneFree said:

There are two paramount considerations, compound and geometry of the tire as both affect the adhesion of the tire to the road surface.


Compound can vary but generally speaking motorcycle tires use a much softer compound that improves friction with the road surface but also reduces tire life as the softer compound wears more than a harder compound. The softer compound used in motorcycle tires relates to the geometry of the tire.





As the comparative photograph shows the motorcycle tire is rounded in shape while the car tire has much squarer corners on it. The rounded surface of the motorcycle tire results in less contact with the road when traveling in a straight line when compared to the car tire (which is a primary reason for the softer compound to increase the friction of a smaller contact surface). In a turn where the motorcycle might be "laid-over" to as much as 45 degrees the contact surface doesn't change but in a car tire. with the square corners, the contact surface can be reduced by as much as 80%. Adding to that loss of fiction contact surface the harder compound of the tire makes cornering very dangerous on the car tire.


Riding straight and level the car tire is superior even with the harder compound but in a turn when the motorcycle is laid over on it's side the reduced contact patch area with the road of the car tire and the harder compound results in a very dangerous situation.


The geometry of a car tire and the harder compounds used simply aren't suitable for a motorcycle (unless it's a trike that doesn't lay-over in the turn).

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Spock001 said:

.... I think that the issue is more complex than safety as to why manufactures don't seem to market much to the general riding community.

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Spock001 said:

I'm a dark sider. I wouldn't consider it for my Street, though. Yes mileage can be quadrupled. For big cruising bikes just under inflate to the "sweet spot pressure."

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Revtom said:

I have a Street 750 with a sidecar. I wear out the middle of the tire since I don’t lean into any turns. Any thoughts on putting a car tire on the rear in this case?

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