Harley Davidson Street Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
548 Posts
Discussion Starter #1

·
Registered
Joined
·
244 Posts
It sounds like there are merits to the practice.

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.
I think that it makes most sense if you ride very frequently for long distances. It seems like the main benefit is having tires that last longer than standard motorcycle tires.
 

·
Premium Member
Joined
·
1,076 Posts
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.
 

·
Registered
Joined
·
548 Posts
Discussion Starter #5
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.
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 :D;)0:)

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

·
Registered
Joined
·
228 Posts
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.
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?
 

·
Premium Member
Joined
·
1,076 Posts
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?


While never litigated to my knowledge I believe there could be a huge liability issue for an owner that put car tires on a motorcycle. Imagine this situation.


A person uses car tires that don't have the rounded edges that motorcycle tires have for cornering and, riding with a passenger, they lose it in a turn due to a lack of tire contact and the passenger dies. They could potentially be found liable in both a civil and possibly in a criminal complaint based upon gross negligence in the death of the passenger. From a criminal standpoint it could very well be considered involutary manslaughter due to gross negligence.


As I said I simply wouldn't do it because it's unsafe. Car tires are not designed to corner like motorcycle tires.
 

·
Premium Member
Joined
·
1,076 Posts
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 :D;)0:)

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


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.
 

·
Registered
Joined
·
281 Posts
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.
I totally agree. One should respect the science behind the design of every machine. Although there is always scope for improvement and modifications, the basic design parameters should not be ignored.
 

·
Registered
Joined
·
38 Posts
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."
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
 

·
Premium Member
Joined
·
1,076 Posts
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."


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.
 

·
Registered
Joined
·
38 Posts
1,000,000 mile club dark sider

Your statements about car tires are similar if not identical to the many critical to proponents statements found on the dark side forum mentioned earlier on this post. Usually but not always the statements fall short of calling proponents "stupid" as is found in your earlier post #8 on this thread, "Simple conclusion. People that do this are stupid IMHO." I have studied the car tire subject extensively, I think thoroughly and for many years academically and practically. There is a science, safety and economics behind the car tire use.
More attention needs to be paid to air pressure and other considerations with a car tire. For a thorough discussion on the proposition of dark side I respectfully, take the liberty to suggest that one start with the dark side forum in order to try to minimize ignorance of the concept. Hope this helps. Spock
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.
 

·
Registered
Joined
·
38 Posts
Sign on to manufacturing

HarleyHoonigan:
Thanks for the conversation on car tires as it promotes the information sharing that can benefit forum members! I don't know why more car tires aren't manufactured for motorcycles. I have seen flat profile tires on drag strip motorcycles and limited other applications, but 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. To get some great, researched info on car tires on motorcycles, you might consider seeking the experienced info in the dark side forum.
Good point on safety, i guess if it really did work out well it would have already been done on a much larger scale.
 

·
Premium Member
Joined
·
1,076 Posts
I have studied the car tire subject extensively, I think thoroughly and for many years academically and practically. There is a science, safety and economics behind the car tire use.
More attention needs to be paid to air pressure and other considerations with a car tire.


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).
 

·
Registered
Joined
·
1,038 Posts
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).
Great points, it does go to show that using motorcycle tires for motorcycles is the way to go might as well stick with how it was intended to be.
 

·
Premium Member
Joined
·
1,076 Posts
.... 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.


Michelin, Dunlap, Bridgestone, Goodyear, and other major automotive tire manufactures do produce motorcycle tires for the general riding community and none of them recommend using a car tire on a motorcycle because it's unsafe.
 
1 - 17 of 17 Posts
Top