Car Tire as Rear Bike Tire - WHATDOYOUTHINK?

kantuckid said:

Hmm. Interesting concept to check the brand name or type of failed parts when deciding who to help @ roadside?

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I also don't understand the logic of not putting the "Anonymous" book online. Some say they fear that non-members would seek help. I say "SO WHAT" . What better way to recruit new mwmbers?!

While I don't post it(meaning the direct link) I have offered to connect people on occassion. Thats what the book is about as long as we try to protect members from being advertised to the world it's all about being nice in the 1st place.

Pragmatists seem to be in short supply on this forum.

A car tire will hold up it's end of the motorcycle just fine. The old bikes all had square profile tires.

The area of a tire on the ground is roughly equal to the weight on the tire and the pressure, leaned or not. The contact patch will be short and wide with the tire vertical and long and thin when leaned over.

There will be a substantial difference in feel. More effort will be required to turn.

The peak lean will be reduced. Few riders can go to peak lean anyway.

No one will criticize someone riding slant 2 airhead, when it's peak corner ability is probably equal to or less than a more modern bike with a car tire. And I am sure that most of you would stop to help.

Rod

ragtoplvr said:

Pragmatists seem to be in short supply on this forum.

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A car tire will hold up it's end of the motorcycle just fine.

So will a brick


The old bikes all had square profile tires.

Do you want your NEW bike to handle like an OLD bike?


The area of a tire on the ground is roughly equal to the weight on the tire and the pressure, leaned or not. The contact patch will be short and wide with the tire vertical and long and thin when leaned over.

In static state this is roughly true. Very few riders care to ride their bikes in a static state.(ie. bike not moving)


There will be a substantial difference in feel.

BINGO


More effort will be required to turn.

DOUBLE BINGO


The peak lean will be reduced.

As will handling all the way up to that point


Few riders can go to peak lean anyway.

Sort of like saying; "few riders can use good brakes to the maximum potential, so let's put crappy brakes on our bikes"



What could possibly go wrong with DIFFERENCE IN FEEL, MORE EFFORT TO TURN, AND REDUCED LEAN ANGLE?

http://www.youtube.com/watch?v=tF5Cttoi7dY


Admittedly, this video shows more the lack of RIDER ability, but the bike should not intentionally be the limiting factor by putting sub standard tires on them.

bdimon said:

I followed a Darksider friend on a Honda GL1800 across West Virginia on Route 50. He runs low pressure in his car tire so that the flat part of the tread will remain flat on the road as the sidewall flexes in the curve. At least, that is what he said it would do.

Here is what I observed. The low pressure caused a lot of bouncing over the bumps as the soft side walls deformed to absorb the impact. When he leaned the bike a little in a corner, the tread did indeed stay flat on the road. However when he leaned over a lot, say 3/4 of the way to grinding the footpegs, the tire tipped onto the edge and only a sliver of the rubber was still on the ground. Hitting a bump in a corner deformed the side wall a LOT! Frankly, I was nervous watching him and worried about the constant sidewall flexing.

At a stop, you can see how the sharp edges of the tire (the right angle from the bottom tread to the sidewall) was wearing and rounding the edge. This made the tread at this juncture thinner than the middle of the tread. So not only are you cornering on a small sliver of tread, the tread is more worn down.

I'll stick with the light side, thank you very much.

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I would think the sidewall would wear out very quickly like that. Auto sidewalls are extremely delicate, compared to a thick motorcycle sidewall. Coupled with low air pressure, I'd guess you'd only get hundreds, not thousands, of miles before failure.

ragtoplvr said:

Pragmatists seem to be in short supply on this forum.

A car tire will hold up it's end of the motorcycle just fine. The old bikes all had square profile tires.

The area of a tire on the ground is roughly equal to the weight on the tire and the pressure, leaned or not. The contact patch will be short and wide with the tire vertical and long and thin when leaned over.

There will be a substantial difference in feel. More effort will be required to turn.

The peak lean will be reduced. Few riders can go to peak lean anyway.

No one will criticize someone riding slant 2 airhead, when it's peak corner ability is probably equal to or less than a more modern bike with a car tire. And I am sure that most of you would stop to help.

Rod

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It's not pragmatism, it's darwinism.

You say a /2 ran a square tire. Well, yeah, but it was 3.5 inches wide. that's 89 mm. A Volkswagen Beetle's tires was twice that width. Comparing a /2 to a modern motorcycle is comparing a propeller plane in the jet age. I'm sure a /2 was a competent mount in it's day, but using a square tire on a modern motorcycle is, at best unnecessarily limiting, and at worst, recklessly dangerous.

Pragmatists seem to be in short supply on this forum.
Perhaps, but this is not about being pragmatic. Its about being smart with your life and bike.

A car tire will hold up it's end of the motorcycle just fine. The old bikes all had square profile tires.
Yes, it'll hold it up, but that is the end of the comparison. So, by that logic, band brakes from old bikes would apply on new bikes?

The area of a tire on the ground is roughly equal to the weight on the tire and the pressure, leaned or not. The contact patch will be short and wide with the tire vertical and long and thin when leaned over.
Here you are simply flat out WRONG. Might apply to cycle tires from the 70's, but not on modern cycle tires. Modern cycle tires are designed to INCREASE the contact patch area as the bike is leaned over. Car tires cannot do this, and old style motorcycle didn't do it either. So why compromise a definite gain?

There will be a substantial difference in feel. More effort will be required to turn.
Perhaps to YOU this is acceptable, but that does NOT apply to all riders in general. A lot of the darksiders think what they accept is acceptable for all.

The peak lean will be reduced. Few riders can go to peak lean anyway.
It's not about PEAK lean. Its about proper control and feel at ALL lean angles. Again, don't assume what is acceptable for YOU applies for all riders.

No one will criticize someone riding slant 2 airhead, when it's peak corner ability is probably equal to or less than a more modern bike with a car tire. And I am sure that most of you would stop to help.
Purely speculative with no basis in actual data!
Oh, by the way, I'll stop to help any rider on the side of the road, no-brand specific or riding style specific.

now to clear things up, I also stop to help harleys and even scooters on the side of the road.

I use Shinko motorcycle tires, not car tires, I have never had one after the mold release wore off, slip on me. But I know they do not have the traction of a Pilot power. Is this wrong? After all, in an emergency situation I am sure the shinko will slide out before the Power.

If I were to use a car tire, I would use a run flat as they have the stiff sidewall. If I planned a run to someplace like Alaska, or a 48 state run, or something like that, it would be on my list of things to consider. If I were heading to Arkansas for fun, no way

Rod

I am just saying, there are valid reasons for using one, other people have valid reasons for what they ride, like an older K75 rather than the latest and greatest.



I

Wait a minute, so the problem with car tires is that it's risky and perhaps stupid to use them on a bike? But isn't riding risky, stupid to many, and not really a necessity? Imagine how badly the Wright brothers would of been flamed if they posted here 110 years ago!

I understand, though I still don't agree. So we agree to disagree. Riding is risky enough, to me there is no rationale to make it any more risky. Though I do tend to wear my tires to the edges, and bevel my boot edges.

Oh, and I ride a 19 year old RS Oilhead, just because it is the right bike for me. Like I am sure the feelings are the same for many people who ride Airheads (still have my 76 RS), K75s and /5s.

Riding a motorcycle around on broad, perpendicular car tires makes perfect sense.....assuming you also embrace the belief that the earth must too be flat.

It's been said before and I'll say it again - it's cheap vs. safe, and in the end, neither side of this 'debate' will budge. Ultimately, Darwin will sort it all out.

To argue it infinitum seems pointless.

The guy who said most riders don't use the lean angle available on their bikes has obviously never seen how the BMW Club of San Diego rides ! Spend an afternoon on Mount Palomar with them and you won't make uninformed statements like that.

Themason said:

The guy who said most riders don't use the lean angle available on their bikes has obviously never seen how the BMW Club of San Diego rides ! Spend an afternoon on Mount Palomar with them and you won't make uninformed statements like that.

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I don't think he limited his meaning to most BMW riders in San Diego.
BMW Club of San Diego ≠ most riders.

There are other motorcycles besides BMW and other motorcycles in places besides San Diego.
And I believe he is correct. Most riders don't use the lean angle available.

ragtoplvr said:

now to clear things up, I also stop to help harleys and even scooters on the side of the road.

I use Shinko motorcycle tires, not car tires, I have never had one after the mold release wore off, slip on me. But I know they do not have the traction of a Pilot power. Is this wrong? After all, in an emergency situation I am sure the shinko will slide out before the Power.

If I were to use a car tire, I would use a run flat as they have the stiff sidewall. If I planned a run to someplace like Alaska, or a 48 state run, or something like that, it would be on my list of things to consider. If I were heading to Arkansas for fun, no way

Rod

I am just saying, there are valid reasons for using one, other people have valid reasons for what they ride, like an older K75 rather than the latest and greatest.



I

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As this has become the thread where we can call people out for anything tire related & especially as to car tires on a bike I am in the "hate run flats crowd" They lack traction at a preferred level and ride terribly, while very pricey and I can attest they will not "run flat" for 50 miles!!! I know this from BMW car experience with them. There is a reason people change them out from the cars. Bad e.g.! As to Shinkos, I run them now , like them & at least for my skill level & fairly mild riding style, find them great tires. They are not made in caves nor do they lack sophisticated rubber compounding materials nor have a crude carcass.
It is a fact that old antique bikes had tires that were sort of tire car like, which gets you not much today...
I'll say again,read the recent Rider article on the car/bike tire thing.

I always ride on the street. In some carefully selected places I get the edge of the tire down usually once in the life of the tire. On the street, I allow a generous safety margin. I have hit enough gravel, grass clippings, leaves, mud, manure and other spilled stuff with chip and seal to convince myself this is a good strategy.

If you guys are cornering at maximum lean angles on the street then I believe you are as crazy as the car tire guys. Like the car tire guys, I am sure there are very few accidents, if any.

Like I said, pragmatism.

That said, I think I would enjoy a run up mount Palomar.

Rod

"Cheap versus Safe"

I'm done with this discussion based on that comment. I have played the "cheap" card tires wise and lost the hand with a busted left leg for it. At least I had a great orthopedic surgeon. He installed the titanium rod in early May and that December I was downhill skiing again.

Yes this needs to be locked up no further sense is being made of it.

ragtoplvr said:

I use Shinko motorcycle tires, not car tires, I have never had one after the mold release wore off, slip on me. But I know they do not have the traction of a Pilot power. Is this wrong? After all, in an emergency situation I am sure the shinko will slide out before the Power.

RodI

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Taking from my experience in the auto industry, I know that it is illegal in the US for a car dealership to install a set of tires that have a lower speed rating than what the vehicle was originally manufactured with. It is both a legal issue and a potential liability lawsuit. For instance:

If a customer came to us with a VW GTI that had worn Z rated tires and requested a set of H rated ties installed, we would have to refuse. This is even true with snow tires, that are available in W and Y ratings, which exceed the Z specification. Can you find a shop that is willing to install H tires? Sure, but it's your neck.

I expect that it's the same with motorcycles. I just put Metzeler Z8s on my R11RT and I'm confident that the tires will not be the limiting factor, should I find myself in an emergency situation.

35634 said:

Wait a minute, so the problem with car tires is that it's risky and perhaps stupid to use them on a bike? But isn't riding risky, stupid to many, and not really a necessity? Imagine how badly the Wright brothers would of been flamed if they posted here 110 years ago!

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Bad analogy. Orville and Wilbur, while testing the flying machine, were using the safety standards they had at the time, meager as they were.

A better analogy for square automotive tires on a motorcycle would be for someone to build a modern muscle car with 500+ horsepower, yet use drum brakes. Anyone in the street rod crowd would consider you an idiot for it.

Delaware.Dave said:

Taking from my experience in the auto industry, I know that it is illegal in the US for a car dealership to install a set of tires that have a lower speed rating than what the vehicle was originally manufactured with. It is both a legal issue and a potential liability lawsuit. For instance:

If a customer came to us with a VW GTI that had worn Z rated tires and requested a set of H rated ties installed, we would have to refuse. This is even true with snow tires, that are available in W and Y ratings, which exceed the Z specification. Can you find a shop that is willing to install H tires? Sure, but it's your neck.

I expect that it's the same with motorcycles. I just put Metzeler Z8s on my R11RT and I'm confident that the tires will not be the limiting factor, should I find myself in an emergency situation.

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Shops routinely refuse to plug-patch otherwise perfectly serviceable tires that have a puncture, requiring you to buy a new one. This offends me greatly and I have gotten into hot arguments with shops over this.

Or how about Costco and their nonsense policy of only putting the tires with the least tread on the front, even on front wheel drive autos. They claim that having the more worn out tires on the rear is too dangerous, that the car could spin out. I have pushed enough cars to the point of loss of traction to know that their claim is without any merit whatsoever. Front wheel drive cars especially will loose traction on the front first unless you do some heroics to provoke the rear to slide ( I know how to do this and it's not easy to do, you basically have to get in really hot until the front slides, then snap off the gas to get the car to rotate, then slam the accelerator down to keep it sliding, and even then some cars like a big fat Avalon won't go there, ever ).
What Costco really wants you to do is to grind those tires down on the front and buy new ones. Similarly with speed ratings on tires. On my older Audis, on the exact same car Audi will specify an H rated tire for the Canadian market and a V rated tire for the US market. An H rating is good to 130 mph. WTF? The car is speed limited to 125 mph in one case and the older one can't break 120 no matter how much road is in front of you. Why do you need a V rated tire?

So much of the tire industry and the auto industry is sleazy that you are almost better off NOT believing what any of the big brand tire shops tell you. They want to make money and nothing else. You have to learn on your own, maybe even take a track day or two. Then you can make informed decisions.