Author Topic: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior  (Read 41125 times)

Online The Mighty Gryphon

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #175 on: March 22, 2020, 11:45:26 AM »
A car tire is designed to operate within a couple degrees of vertical, whereas a moto tire needs to be able to operate at angles as great as 60 degrees from vertical.  Because of that, traction is engineered into the profile over a much greater area of the cross section of the tire.

Car tires are engineered to provide traction over a large flat contact patch, moto tires are designed to provide traction over a much smaller contact patch that varies widely in position around the cross section.  They are also required to handle larger side loads relative to the size of the contact patch.  Because of those requirements, the rubber compounds used are softer and necessarily wear faster.

The problem with a car tire is that as the bike is leaned into a turn and rolls onto the square corner of the tire, it is losing contact area, and what contact is made is through a harder less tractable rubber compound.  Not a good situation considering that as that is happening, the side loading on the tire is increasing as well, increasing the risk of a low side.  All it takes is one such accidental drop to wipe out any possible savings you might achieve using car tires on your bike.

  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline Past-my-Prime

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #176 on: March 22, 2020, 01:17:04 PM »
I'll give PmP $0.02 for it if he accepts PayPal.

Hahaha an affirming response from Laitch is worth more than mere $$.  44271

It seemed to me that this thread went off the rails about 8 pages ago. . .

Today was more of a "go ice fishing" day as opposed to doing anything worthwhile.
  • North Shore of Lake Superior
  • BRICK: 1989 K75 RT - Rocinante; NONBRICK: 2007 F650 GS Dakar - not yet named

Offline k

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #177 on: March 22, 2020, 03:37:01 PM »
A car tire is designed to operate within a couple degrees of vertical,

 :threadjacked :threadjacked :threadjacked :threadjacked :threadjacked

QUIT IT. THAT'S OFF-TOPIC FOR THIS THREAD.

GO CREATE YOUR OWN THREAD TO BASH DARKSIDING, BUT STAY OUT OF THIS ONE.

Where are the moderators?

The function of a moderator is to keep a conversation on track, not remove profanity or temper strong words.
  • Indiana
  • 1985 K100

Offline Laitch

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #178 on: March 22, 2020, 03:55:18 PM »
Where are the moderators?
The function of a moderator is to keep a conversation on track, not remove profanity or temper strong words.
I'm a moderator and I'm sitting in a chair.
You're off-topic. Get back on topic.
  • Along the Ridley in Vermont.
  • 1995 K75 79,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline k

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #179 on: March 22, 2020, 04:04:50 PM »
I'm a moderator and I'm sitting in a chair.
You're off-topic. Get back on topic.

This is a waste of time.
  • Indiana
  • 1985 K100

Offline Past-my-Prime

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #180 on: March 22, 2020, 04:25:42 PM »
This is a waste of time.

https://ridermagazine.com/2016/05/20/tales-from-the-dark-side-putting-car-tires-on-motorcycles/

Here is a good resource, with lots of pictures and some nice graphs. It's a reasonable place to spend a little time.

Unless I was intending on driving my motorcycle in a straight line at a slow speed 100% of the time, the $ savings is not worth it to me.

You may observe that there are eight pages of posts on the possiblity of putting car tires on motorcycles, mostly recommending that it's not advisable.

If you happen to be looking for validation of the idea, it doesn't seem that this is where you will get that. But in the letters responding to the original author of the article I referenced above, there are lots of people who swear by it, so everyone has their own idea which is a good thing.

Finally, in answer to your point, internet forums are not widely known as a useful way to spend one's time. Heck, without this forum I still wouldn't know I needed to replace my driveshaft and would be blithely motoring along! (Until, that is, I wasn't).
  • North Shore of Lake Superior
  • BRICK: 1989 K75 RT - Rocinante; NONBRICK: 2007 F650 GS Dakar - not yet named

Online The Mighty Gryphon

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #181 on: March 22, 2020, 04:32:20 PM »
Finally, in answer to your point, internet forums are not widely known as a useful way to spend one's time. Heck, without this forum I still wouldn't know I needed to replace my driveshaft and would be blithely motoring along! (Until, that is, I wasn't).

MODERATOR ALERT: OFF TOPIC POST BELOW!!!

+1  I shudder to think how much extra space I would have in my garage and cash in my bank account were it not for spending time here.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline Laitch

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #182 on: March 22, 2020, 05:12:40 PM »
The incidence of hijacking in this thread has increased alarmingly. I suggest all off-topic posters consider the suffering caused by their behavior and spank themselves into a state of contrition by whichever means can be safely deployed during this contagion then return with more advice.



  • Along the Ridley in Vermont.
  • 1995 K75 79,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline ^Adrninistrator

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #183 on: March 22, 2020, 06:14:38 PM »
Stay on-topic.  Another of display of off-topic defiance will result in you clicking here to get on the grid before you are banned for life.
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Offline Chaos

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #184 on: March 22, 2020, 06:37:59 PM »
If I go darkside and fill my tyres with helium will only dogs be able to hear my burnouts?
  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
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Offline k

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #185 on: March 28, 2020, 07:06:52 PM »
You may observe that there are eight pages of posts on the possiblity of putting car tires on motorcycles, mostly recommending that it's not advisable.
.- .-.. .-..     --- ..-.     .-- .... .. -.-. ....     .- .-. .     .. .-. .-. . .-.. . ...- .- -. - --..--     ..- -. ... --- .-.. .. -.-. .. - . -.. --..--     .- -. -..     --- ..-. ..-. - --- .--. .. -.-. .-.-.-

Quote
Unless I was intending on driving my motorcycle in a straight line
.- .-.. .-..     --- ..-.     .-- .... .. -.-. ....     .- .-. .     .. .-. .-. . .-.. . ...- .- -. - --..--     ..- -. ... --- .-.. .. -.-. .. - . -.. --..--     .- -. -..     --- ..-. ..-. - --- .--. .. -.-. .-.-.-

Quote
If you happen to be looking for validation of the idea,
.. --     -. --- - .-.-.-
  • Indiana
  • 1985 K100

Online The Mighty Gryphon

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #186 on: March 28, 2020, 08:23:47 PM »
.- .-.. .-..     --- ..-.     .-- .... .. -.-. ....     .- .-. .     .. .-. .-. . .-.. . ...- .- -. - --..--     ..- -. ... --- .-.. .. -.-. .. - . -.. --..--     .- -. -..     --- ..-. ..-. - --- .--. .. -.-. .-.-.-
.- .-.. .-..     --- ..-.     .-- .... .. -.-. ....     .- .-. .     .. .-. .-. . .-.. . ...- .- -. - --..--     ..- -. ... --- .-.. .. -.-. .. - . -.. --..--     .- -. -..     --- ..-. ..-. - --- .--. .. -.-. .-.-.-
.. --     -. --- - .-.-.-

OMG!  We have a ham radio operator that not one other ham in the entire world will talk to. 

I wonder why???
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline Martin

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #187 on: March 28, 2020, 10:12:52 PM »
--. --- / -.- / --. ---
.-. . --. .- .-. -.. ... / -- .- .-. - .. -. .-.-.-
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Online The Mighty Gryphon

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #188 on: March 28, 2020, 10:14:34 PM »
Martin, cut it out!
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline Martin

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #189 on: March 28, 2020, 10:22:22 PM »
jIQoS martin quv, vIchID gryph jIH wej jIQaHlaH
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Online The Mighty Gryphon

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #190 on: March 28, 2020, 10:38:51 PM »
I'm pretty sure that last post wasn't on topic.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline Martin

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #191 on: March 28, 2020, 10:50:14 PM »
 I'll go confine myself as an act of contrition.
Regards a slightly bored but contrite Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline daveson

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #192 on: March 28, 2020, 11:04:58 PM »
Ist das English Esperanto im Morse code?
Das ist alIvays ein goot idea ven vie nicht haben logic fur zu continu ein idea.

Auto tyres an motorbike ist save money ven du nicht haben pay fur hospital bills.
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Offline Past-my-Prime

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Re: Fidding a 18" x 4.5" Rear Moto Wheel Widda Car Tior
« Reply #193 on: March 28, 2020, 11:15:37 PM »
Hey Indiana k I'm super glad you came back; I was concerned that you might have left this thread permanently. I really did not mean to be offensive.

Have you been able to locate any car tires that would fit the rear wheel (and clear the swingarm) on a k75?

I looked at a bunch of tire sites and there do not appear to be a bunch of 4.5 inch wide, 18 inch diameter tires at all. Or anyone else?
  • North Shore of Lake Superior
  • BRICK: 1989 K75 RT - Rocinante; NONBRICK: 2007 F650 GS Dakar - not yet named

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