Auto Tire on the Rear, GL1800


Information and questions on GL1800 Goldwings (2001-Present)
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Defender
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2002 Gl1800

Re: Auto Tire on the Rear, GL1800

Post by Defender » Wed Oct 11, 2017 5:47 pm



Thanks for the info, my bike had a 55 on it when I bought it but alas, it is worn out, I'm looking for info and appreciate the input. I do like the car tire ride and feel so will probably buy another ct.



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823JIM
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Re: Auto Tire on the Rear, GL1800

Post by 823JIM » Sun Nov 12, 2017 8:11 am

Road and Track has positive outlook on the CT debate.

http://www.roadandtrack.com/car-culture ... torcycles/
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wing rider 2012
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Re: Auto Tire on the Rear, GL1800

Post by wing rider 2012 » Sat Nov 18, 2017 2:47 pm

Let me start this off by saying that I really don't care what type of tire you install on your bike. A car tire and a motorcycle are fundamentally different and there is a reason for this, riding on 4 wheels and riding on 2 wheels are fundamentally different. I believe that if car tires were the same as motorcycle tires then Honda would install them on their bikes. There is a lot of science that goes into tires, both for cars and motorcycles. Why are motorcycle tires manufactured with a rounded design and car tires manufactured with a flat design? It is due to the, again, fundamental difference between the handling of a motorcycle and that of a car. This difference is noticed more in cornering than on a straight piece of road. The "G" forces exerted on a motorcycle tire in a curve is about 1.5 G's compared to a car in the same curve their tire at 1 G. This is why a car tire can have a more flexible sidewall than a motorcycle. The down force and the side forces exerted on a motorcycle tire in a curve is called "Camber Thrust" this is why a motorcycle tire will have stiffer sidewalls than a car tire. This downward force creates friction and friction creates grip. So, a car tire may be fine for your style of riding, but make sure you use the right equipment for your style of riding.

Here is a good article about this: http://www.genjac.com/BoomerBiker/Two%2 ... hysics.htm
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823JIM
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Re: Auto Tire on the Rear, GL1800

Post by 823JIM » Sat Nov 18, 2017 8:39 pm

wing rider 2012 wrote:
Sat Nov 18, 2017 2:47 pm
----------- A car tire and a motorcycle are fundamentally different ----------- So, a car tire may be fine for your style of riding, but make sure you use the right equipment for your style of riding.

Here is a good article about this: http://www.genjac.com/BoomerBiker/Two%2 ... hysics.htm
The style of riding that us who are using car tires is called "touring", and mostly two up touring, also trailer towing on long trips. I would not at all suggest a CT be used on a sport bike/crotch rocket or road race bike. As I am sure you do not believe the lean angles and G loads are the same with the vast difference of these styles of riding. I do not believe attempting the lean angles you imply in tire loads are either wise or safe in two up riding of a large touring bike such as a Goldwing. So yes, as you stated style of riding makes a large difference in tire choice. But I prefer the better traction and braking, practically on wet roads the car tire offers on a full size touring motorcycle.

And my bike does handle just fine in the curves, last photo is wife and I on Moonshine 28.
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wing rider 2012
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1998 GL1500 Aspy
1985 Venture Royal 1300
1979 GL1000

Re: Auto Tire on the Rear, GL1800

Post by wing rider 2012 » Tue Nov 21, 2017 1:00 pm

823JIM wrote:
Sat Nov 18, 2017 8:39 pm
wing rider 2012 wrote:
Sat Nov 18, 2017 2:47 pm
----------- A car tire and a motorcycle are fundamentally different ----------- So, a car tire may be fine for your style of riding, but make sure you use the right equipment for your style of riding.

Here is a good article about this: http://www.genjac.com/BoomerBiker/Two%2 ... hysics.htm
The style of riding that us who are using car tires is called "touring", and mostly two up touring, also trailer towing on long trips. I would not at all suggest a CT be used on a sport bike/crotch rocket or road race bike. As I am sure you do not believe the lean angles and G loads are the same with the vast difference of these styles of riding. I do not believe attempting the lean angles you imply in tire loads are either wise or safe in two up riding of a large touring bike such as a Goldwing. So yes, as you stated style of riding makes a large difference in tire choice. But I prefer the better traction and braking, practically on wet roads the car tire offers on a full size touring motorcycle.

And my bike does handle just fine in the curves, last photo is wife and I on Moonshine 28.
Camber thrust is related to speed, the higher the speed in a curve the greater the camber thrust, however, this dynamic applies to all speeds on a motorcycle due to the fundamental way a motorcycle takes a curve. It is the leaning action of a motorcycle that creates camber thrust and this force is applied regardless of speed. This is the reason motorcycle tires have a stiffer side wall than a car tire. A car tire in a curve will exhibit sidewall flexing, and depending on the speed and the curve the tire will flex to maintain a flat pattern on the road surface, that is until, friction is broken or sidewall failure, there is no downward force being applied to the tires with the exception of the weight of the car. For a motorcycle, entering a curve at the same speed of any car the dynamics are completely different. You have 3 actions at play here, gravity, centrifugal force and the gyroscopic action of the wheels and tires. Seeing how your center of gravity has changed, you will have gravity trying to pull you down, centrifugal force will exert a force parallel with the bike, and the gyroscopic action will try and upright the bike, this creates a camber force which will be exerted onto the sidewall of the tires.
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823JIM
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Re: Auto Tire on the Rear, GL1800

Post by 823JIM » Tue Nov 21, 2017 5:15 pm

wing rider 2012 wrote:
Tue Nov 21, 2017 1:00 pm
823JIM wrote:
Sat Nov 18, 2017 8:39 pm
wing rider 2012 wrote:
Sat Nov 18, 2017 2:47 pm
----------- A car tire and a motorcycle are fundamentally different ----------- So, a car tire may be fine for your style of riding, but make sure you use the right equipment for your style of riding.

Here is a good article about this: http://www.genjac.com/BoomerBiker/Two%2 ... hysics.htm
The style of riding that us who are using car tires is called "touring", and mostly two up touring, also trailer towing on long trips. I would not at all suggest a CT be used on a sport bike/crotch rocket or road race bike. As I am sure you do not believe the lean angles and G loads are the same with the vast difference of these styles of riding. I do not believe attempting the lean angles you imply in tire loads are either wise or safe in two up riding of a large touring bike such as a Goldwing. So yes, as you stated style of riding makes a large difference in tire choice. But I prefer the better traction and braking, practically on wet roads the car tire offers on a full size touring motorcycle.

And my bike does handle just fine in the curves, last photo is wife and I on Moonshine 28.
Camber thrust is related to speed, the higher the speed in a curve the greater the camber thrust, however, this dynamic applies to all speeds on a motorcycle due to the fundamental way a motorcycle takes a curve. It is the leaning action of a motorcycle that creates camber thrust and this force is applied regardless of speed. This is the reason motorcycle tires have a stiffer side wall than a car tire. A car tire in a curve will exhibit sidewall flexing, and depending on the speed and the curve the tire will flex to maintain a flat pattern on the road surface, that is until, friction is broken or sidewall failure, there is no downward force being applied to the tires with the exception of the weight of the car. For a motorcycle, entering a curve at the same speed of any car the dynamics are completely different. You have 3 actions at play here, gravity, centrifugal force and the gyroscopic action of the wheels and tires. Seeing how your center of gravity has changed, you will have gravity trying to pull you down, centrifugal force will exert a force parallel with the bike, and the gyroscopic action will try and upright the bike, this creates a camber force which will be exerted onto the sidewall of the tires.
Yeah, what you said.. "the tire will flex to maintain a flat pattern on the road surface" leaving a larger foot print, more rubber on the ground. "that is until, friction is broken or sidewall failure," more rubber on ground equals more friction (aka grip) which is the whole point. Have never heard of car tire side wall failure on a motorcycle. I realize I am not looking a this in the engineering and scientific terms that you are, just saying what I know works from experience (over 30,000 miles on CT on this bike). Sorry if I'm sounding argumentative.
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wing rider 2012
Posts: 212
Joined: Thu May 16, 2013 4:49 pm
Location: Medford, Oregon
Motorcycle: 2012 GL1800 Level I Blue/Silver
1998 GL1500 Aspy
1985 Venture Royal 1300
1979 GL1000

Re: Auto Tire on the Rear, GL1800

Post by wing rider 2012 » Tue Nov 21, 2017 7:22 pm

823JIM wrote:
Tue Nov 21, 2017 5:15 pm
wing rider 2012 wrote:
Tue Nov 21, 2017 1:00 pm
823JIM wrote:
Sat Nov 18, 2017 8:39 pm


The style of riding that us who are using car tires is called "touring", and mostly two up touring, also trailer towing on long trips. I would not at all suggest a CT be used on a sport bike/crotch rocket or road race bike. As I am sure you do not believe the lean angles and G loads are the same with the vast difference of these styles of riding. I do not believe attempting the lean angles you imply in tire loads are either wise or safe in two up riding of a large touring bike such as a Goldwing. So yes, as you stated style of riding makes a large difference in tire choice. But I prefer the better traction and braking, practically on wet roads the car tire offers on a full size touring motorcycle.

And my bike does handle just fine in the curves, last photo is wife and I on Moonshine 28.


Camber thrust is related to speed, the higher the speed in a curve the greater the camber thrust, however, this dynamic applies to all speeds on a motorcycle due to the fundamental way a motorcycle takes a curve. It is the leaning action of a motorcycle that creates camber thrust and this force is applied regardless of speed. This is the reason motorcycle tires have a stiffer side wall than a car tire. A car tire in a curve will exhibit sidewall flexing, and depending on the speed and the curve the tire will flex to maintain a flat pattern on the road surface, that is until, friction is broken or sidewall failure, there is no downward force being applied to the tires with the exception of the weight of the car. For a motorcycle, entering a curve at the same speed of any car the dynamics are completely different. You have 3 actions at play here, gravity, centrifugal force and the gyroscopic action of the wheels and tires. Seeing how your center of gravity has changed, you will have gravity trying to pull you down, centrifugal force will exert a force parallel with the bike, and the gyroscopic action will try and upright the bike, this creates a camber force which will be exerted onto the sidewall of the tires.
Yeah, what you said.. "the tire will flex to maintain a flat pattern on the road surface" leaving a larger foot print, more rubber on the ground. "that is until, friction is broken or sidewall failure," more rubber on ground equals more friction (aka grip) which is the whole point. Have never heard of car tire side wall failure on a motorcycle. I realize I am not looking a this in the engineering and scientific terms that you are, just saying what I know works from experience (over 30,000 miles on CT on this bike). Sorry if I'm sounding argumentative.
I completely agree with your post, I know a lot of riders that are Darksiders, I don't have a problem with that. I was just trying to point out the differences between the two tires and the science that goes into them. Agreed, most touring bikes can run a car tire with no problem, due to the nature of touring.
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823JIM
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Motorcycle: 2003 GL1800 Goldwing
1978 KZ650 (needs restoring)

Re: Auto Tire on the Rear, GL1800

Post by 823JIM » Tue Nov 21, 2017 10:18 pm

Thank you wing rider 2012 for the good discussion and your input on this subject. Been nice talking with ya, and thank you for your service to this country.
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