Going to the Dark Side

[Fred W]

Trying to wrap my head around what you're saying -- do you mean that a contact patch of a car tire, say 16 square inches (2" x 8") is no better than the contact patch of a motorcycle tire, say 4 square inches (2" x 2")?
...that given an emergency (lock-up) situation a car tire wouldn't stop faster than a motorcycle tire?

Or are you simply saying that for any given amount of equal pressure applied to the brake pedal, the car tire wouldn't provide any better stopping power than a bike tire?

Unfortuantely, we don't have enough information to say one way or another if the bike will stop faster with a car tire (or slower for that matter). I was merely pointing out that the increase in contact patch area does not necessarily equate to an increase (or decrease) in friction (traction) since the downward force will then be spread over a greater area.

One unknown variable is the rubber compound, which will result in varying coefficients of friction. Another is the tread geometry and how that interacts with a given road surface. Too many unknowns to make a blanket statement.

But one thing is for sure, if an FJR with a car tire is set on a moving conveyor belt, it will NOT fly!

 

[Khunajawdge]

So let's consider the straight line emergency braking scenario:
If the contact patch on a 8.5-inch CT is great then the 1-inch patch on a MC tire, is it not logical to assume that the braking power in the CT is greater than on the motorcycle tire?

Variables:

1. Weight/sq. inch of contact patch and the effect of same on friction with the roadway

2. Tire compound. The "stickiness" of the tire to the road and its effect of friction.

3. Does the bigger contact patch on the CT overcome any of these variables?

Discuss: [as I pour myself another cup of joe]

Show your work.

Ah Say there Bob, good to see you over here stirring things up with Eric. I knew you could do it! :clapping:

My approach to the tire wear dilemna(sp?) in this 2009 year, is to buy 2 new sets of discontinued AVON Azaros at a next to cost of the weight of the rubber from J&P cycles, and store the sets as spares until I need 'em. I think in the long run, my tire cost will be similar to yours running that car tire on the rear of your bike for 40,000miles. You will still need to replace your front tire at near to the normal MC wear intervals of 10,000 miles, No? Unless of course, you plan to re-work the front end of your bike to put a car tire up there as well? Would a HD Fat Boy triple tree have enough clearance on an FJR front end without modifying the gas tank fairing etc? If you do all that, then me thinks, the tire patch dilemna(sp?) may become even more contentious, especially when leaned over... but, you will probably get much more tire wear/$$$ savings out of a single set of tires, than my proposed approach above. :glare:

 

[palerider]

But one thing is for sure, if an FJR with a car tire is set on a moving conveyor belt, it will NOT fly!

You don't know until you try.

 

[user 213]

If you're running a MC tire in back and, in the middle of any kind of turn - at speed - if the rider hits the rear brake hard it's a pretty good assumption he's going down in a low side. With a CT in back, the same thing happens. The rear end breaks out in both scenarios.
If you hit the rear brake hard in a straight line stop you'll stay up but you'll just skid. A lot. So let's consider the straight line emergency braking scenario:

If the contact patch on a 8.5-inch CT is great then the 1-inch patch on a MC tire, is it not logical to assume that the braking power in the CT is greater than on the motorcycle tire?

Variables:

1. Weight/sq. inch of contact patch and the effect of same on friction with the roadway

2. Tire compound. The "stickiness" of the tire to the road and its effect of friction.

3. Does the bigger contact patch on the CT overcome any of these variables?

Discuss: [as I pour myself another cup of joe]

Show your work.

Weight transfer is still the largest factor in motorcycle braking. Regardless of how much back tire you have, if you are braking correctly, (for a panic stop or other scenario where you intend to stop), using both brakes, enough weight will shift off the rear to make contact patch moot.

However, on a trike, the big car tires become your major braking force and the sheer weight of the trike will overwhelm most front brakes and simply burn up pads quickly. Very different dynamics. Nobody I know can stoppie a trike.

The wider CT may provide more braking before lock up. Wether that actually translates to a shorter stopping distance is another thing. If you're not locking up the moto tire, then you never exceeded it's braking potential.

ABS is a wonderful thing. Maybe I'll try some ABS stops with the CT in the future to see how it responds.

 

[RadioHowie]

Maybe I'll try some ABS stops with the CT in the future to see how it responds.

Remember what I said about going through Heaven's gates backwards and on fire???

Be careful, and report back soon!

 

[SkooterG]

Damn. This thread is better than reality TV.

 

[Fred W]

Remember what I said about going through Heaven's gates backwards and on fire???

Awwww, who the heck wants to go to Heaven anyway? Nobody interesting there...

 

[palerider]

Remember what I said about going through Heaven's gates backwards and on fire???

Awwww, who the heck wants to go to Heaven anyway? Nobody interesting there...

Abe Lincoln's there.

 

[Fred W]

Remember what I said about going through Heaven's gates backwards and on fire???

Awwww, who the heck wants to go to Heaven anyway? Nobody interesting there...

Abe Lincoln's there.

If you say so...

 

[user 213]

Abe Lincoln's there.

Hey! No politics. No religion either, fwiw. :dribble:

If you ride an ABS FJR and don't know what it feels like when the ABS engages, you need to know. It will help you do the right thing when it happens in crisis/survival mode.

Now, I'm not saying go ride in the snow or anything. :devil: But that will do it. Easy on the front brake in the snow.

 

[El Toro]

I've also been watching this thread with interest. I have decided to do a "reverse test" of the moto vs car tire. I am taking my Pontiac Formula Firebird to the tire shop today and mounting 4 Avon Storms on it! I will report back and let you know how well the car did with moto tires. I just hope my front end doesnt wobble or otherwise track or wear strangely. :glare:

:haha: :lol2: :rofl: :yahoo: :lol2: :crazy:
+1 (on the post counter) :download:

 

[user 213]

I've also been watching this thread with interest. I have decided to do a "reverse test" of the moto vs car tire. I am taking my Pontiac Formula Firebird to the tire shop today and mounting 4 Avon Storms on it! I will report back and let you know how well the car did with moto tires. I just hope my front end doesnt wobble or otherwise track or wear strangely. :glare:

I was gonna leave this one alone, but...

A. Start your own thread on the Firebird list, eh? <_<

B. Dayam, I wish I had all the cash you must have.

C. As long as you drive within the tire's envelope, it's all good.

D. Check out the Subie guys putting 15" temp spare wheels on old Brats. That can't be safe! :lol: :lol:

 

[n1acguy]

What an interesting thread. I don't have any reason to try it myself since I never seem to wear tires out. I replace them because they get too old. I really hope to ride more.

I'm amazed at how thin the carcass of a motorcycle tire is. Not much puncture resistance there at all. A car tire should be way more resistant to punctures. Might even be safer in a straight line enviroment.

 

[jekirby]

Even if the contact patch is larger assuming the total weight of the bike is unchanged, then the weight per square inch of contact area will be less with the CT. The total amount of force has to stay the same.

Had an exercise in one of my physics classes in college that showed that area had nothing to to with friction (if I worded that correctly). The coeficient of sliding friction did not change. I remember chalking it up to how things that work out on paper does not always jive with common sense-or what we think should be common sense. I think that Fred's above statement helps to explain that. BTW I couldn't begin to show you my work, but I did get a A in the class.

 

[Flylooper]

Just tryin' to understand the point you were trying to make.

Someone commented about how he has seen countless CT equipped moto riders go sliding through intersections because they couldn't stop.

I just sort of took the comment and ran with it.

1. I'm not an engineer, machinist, wrench, or grease monkey (and I envy to the nth degree those of you who are);

2. I don't experiment with my bike, mostly because I can't;

3. I consider myself a LD rider, as opposed to seeking out the twisties and seeing how fast I can get through them;

4. My 401(k) has become a 201(k); hence my interest in getting max mileage out of a rear tire, and so for me...

5. This is a very interesting thread.

 

[SouthernCruizer]

I've also been watching this thread with interest. I have decided to do a "reverse test" of the moto vs car tire. I am taking my Pontiac Formula Firebird to the tire shop today and mounting 4 Avon Storms on it! I will report back and let you know how well the car did with moto tires. I just hope my front end doesnt wobble or otherwise track or wear strangely. :glare:

I was gonna leave this one alone, but...

A. Start your own thread on the Firebird list, eh? <_<

B. Dayam, I wish I had all the cash you must have.

C. As long as you drive within the tire's envelope, it's all good.

D. Check out the Subie guys putting 15" temp spare wheels on old Brats. That can't be safe! :lol: :lol:

*********************************************************

I have to come clean on this. I really didn't think of this test on my own. It was first done by a HD rider in Idaho. I discovered this on a HD forum. He installed 4 moto tires on his AMC Matador. Unfortunately, after 11 months of testing, the results of his test were totally inconclusive, as he hauled the car everywhere he went on a trailer, so the damn tires never actually contacted the road!! :blink:

I will be scouting areas for twistys to run my moto vs car tire test. I will report back shortly.

P.S. anyone know a good Firebird mechanic in the Gulf Coast area? I think my engine is starting to make a "ticking" sound.

 

[Flylooper]

My Concours-riding buddy in Washington posted the following, which I snipped away from his introductory post here.

Ok.
New to this forum then. Live in the PNWet, west WA. Kinda restrictive for a new member to be able to post but the guardians of the gates have a reason. Was alerted to the Darkside posts by 'flylooper' and read some.

I am a Darksider and tho yet to have an FJR keep expecting that a '06 or newer will be the replacement for the Concours.

240k mi total on two Concours. Also ride dual sport and dirt. 26k mi now on the CarTire on the Connie and IMO it is better traction than any sport touring tire I have used. Better vertical, leaned over, braking, acceleration, whatever. We have wet roads and it is superior in limited traction conditions. Better traction in all conditions and attitudes. Been to TX twice this year. We have some very good, challenging, twisty and elevations in our roads in WA state. The CT has been very good for me. I am not the most fast and neither in the rear of the pack.

Not the most or ever set a record but after the 5th decade of riding I have developed pretty good survival skills and general riding knowledge.

If I really have to have 25 posts here ?? before responding to a thread.. well.... maybe.

Dan P

Graham WA

 

[Danodemotoman]

Thanks Bob for posting my newbie intro. I can now post and reply to topics. :clapping: The intro thread was not the best thread to state my CT experience I guess.

But yeah it has been a rewarding experiment. No longer an experiment tho.

I had no idea that the traction advantage would be so clear. The minor negative so far has been the required extra input required to initiate the turn. Ya get used to it like riding a different moto. The low cost per mile is just one plus and not the deciding factor for me. The improved traction is.

I will make a general statement that using the widest CT may not be the best choice. Using one equal or close to stock width may be the best choice.

I have no data just experience with my moto with my tire (limited) choices..

So having just gone Darkside last April I am still learning. Part of the education is that not all tires have the same handling characteristics (DOH!). We all know that and it also applies to using the different car tire/brands/models.

The aging platform of the C-10 Concours is still capable of enjoyable sport touring. CT limitations have to do with the narrow width of the Connie tire clearances/wheel size and flexing of the CT sidewalls. This flexing I am finding out has different amounts and rate in one tire to another. The Federal tire I now use has hardly any feedback with sidewall flex.

Ride on my brothers.

Dan P

My Concours-riding buddy in Washington posted the following, which I snipped away from his introductory post here.

 

[Bulldog9]

Been following this with interest, and while I learn much on these forums, and am a fan of innovation, this is one of those "NO WAY" things for me. I can see this on a fully dressed Cruiser/Touring bike, or Chopper/Custom bike, but not an FJR, at least not how I ride.

I'm interested in this becasue I anticipate an 900 Mile round trip every weekend, from July-Dember next year, and dont want to burn through a set of tires every 2 months. Not sure what I will do yet, but plan a new set of rubber in June, and hope to make them safely last till December, I figure at least 10K of mileage, plus side trips, day trips, etc. I will only be about 80 miles to the NC side of The Dragons Tail/Cherohola and that whole area, so I plan a few day trips out there in between.

I still want the ability to carve and ride my normal pace and to the bikes capabilities, so no dark side for me......... But here's to innovation!

 

[user 213]

Been following this with interest, and while I learn much on these forums, and am a fan of innovation, this is one of those "NO WAY" things for me. I can see this on a fully dressed Cruiser/Touring bike, or Chopper/Custom bike, but not an FJR, at least not how I ride.
I'm interested in this becasue I anticipate an 900 Mile round trip every weekend, from July-Dember next year, and dont want to burn through a set of tires every 2 months. Not sure what I will do yet, but plan a new set of rubber in June, and hope to make them safely last till December, I figure at least 10K of mileage, plus side trips, day trips, etc. I will only be about 80 miles to the NC side of The Dragons Tail/Cherohola and that whole area, so I plan a few day trips out there in between.

I still want the ability to carve and ride my normal pace and to the bikes capabilities, so no dark side for me......... But here's to innovation!

So how are you on tires so far? The PR2s have an increasingly good rep for life, though not for great handling after about half the wear, or fantastic wet traction. The BT-021 rear does very well on life too, (front sucks moist ass though), and has nice traction too.