My car tire impressions- for real

[dantama]

Originally Posted by ridemslow

Kudos Dan. Figure if anyone could make this comparrison, and still have the nads to post it, it would be you, and you did. What you say is all right on, so one must take it as it comes, see for themselves. I am a Darksider, and I actually like the Car tire feel, but thats just me. Dam good post Dan.

Thanks Ridemslow and others.

The posts made me curious about air pressure, so I went and checked. I do have a lot of pressure in it, I asked for 34, didn't check it myself, and have 39psi. I'll knock it down to 32 just to get more contrast and see if it improves.

Some posters have experienced the same thing as me, but got used to it. As I said, all of my experiences could be gotten used to.

I'll continue to evaluate, but I think at times impressions that come with the highest contrast are sometimes the most valid. Kind of like not noticing the junk in your own neighborhood because you got used to it, then moving away. When you come back for a visit you see things that you didn't notice when you were used to it all.

With what I've experienced so far, I don't think that there is anything that is MORE positive, other than mileage, and some things are worse, like the following ruts that I and Idaho experience. I am pleased to hear that he doesn't find it a problem on dirt roads. I figured if it was that noticeable on pavement, it would have a mind of it's own on a rutted up dirt road. And I love riding on dirt roads.

I'm sure that for one very skeptical poster, I can find a way to prove the edge, flat, edge effect. I never claimed that I was riding on the side wall, and I never said anything about tar snakes? But if you take a basketball (extreme I know) and roll it side to side a few inches, then do the same thing with a shoe box, you'll see that the flat one rides up on the edges. That is an extreme example, but that is what I feel, though to a lesser degree. I'll find a way to prove it, just cause I hate being told I'm up in the night, I know bikes and riding dynamics pretty well, and I defiantly felt something different, and something had to be causing it. I would think that taking your spare tire out of your trunk and rolling it side to side at the angles I was turning would show it, I'll look into it.

As I'm a cheap bastard, I'm doing this for the extra miles, and that might be valid enough. But my 5 day test doesn't show a single improvement, other than long miles. I'll lower the pressure, and be open to perceptions changing. If the perceptions are grounded in fact, then I'll get used to the changes, but they will still be there. Perhaps what I feel isn't grounded in fact, and I'm up in the night and was having perceptions. I'll figure out a way to prove it one way or another.

Now off to lower the pressure.

[pooker]

I'm sure that for one very skeptical poster, I can find a way to prove the edge, flat, edge effect. I never claimed that I was riding on the side wall, and I never said anything about tar snakes? But if you take a basketball (extreme I know) and roll it side to side a few inches, then do the same thing with a shoe box, you'll see that the flat one rides up on the edges. That is an extreme example, but that is what I feel, though to a lesser degree. I'll find a way to prove it, just cause I hate being told I'm up in the night, I know bikes and riding dynamics pretty well, and I defiantly felt something different, and something had to be causing it. I would think that taking your spare tire out of your trunk and rolling it side to side at the angles I was turning would show it, I'll look into it.

Now off to lower the pressure. [/quote]

Lets see how it is with a lower pressure.
But I had to laugh at your analogy, shoe box and ball.
Also if you place your spare on the ground and move it side to side,.......... I will see the edge, flat, edge.
Yeah! what did you expect,.....there is no weight on the tire.
Like said earlier, the side wall bends on a car tire, thus no edge!!
Take any corner and you will still have over 4 inches of rubber in contact with the road.

[phred]

I'm still on a m/c tire, so I don't really have a dog in this fight, but I've done a lot of research in considering a c/t. Videos like this one seem to show that the c/t does in fact ride up on the edge as the rider leans.

[pooker]

Originally Posted by phred

I'm still on a m/c tire, so I don't really have a dog in this fight, but I've done a lot of research in considering a c/t. Videos like this one seem to show that the c/t does in fact ride up on the edge as the rider leans.

The tire is stiff ,..............I will guarantee that that rider has why too air in that tire.
This is not a good example of how a car tire performs.

[sonny]

For those of you who remember the 1960's and 1970's, some folks have told me about my part in them, all bike tires had square shoulders or edges. We would kinda drop into a curve. And rain grooves on the interstates would feel like the back wheel was loose. Some folks even put VW tires on back. I quit riding in '84 for about 8 years and when I got back the 1st bike I bought had the round shoulder tires. It made me crazy for months. Every time I shifted my hip pockets on the seat the flipping bike would change lanes, and some times change it back. I did finally get used to the difference. But I am really considering going to a CT. For one $100+ for 6 to 10k is out of hand and two I kinda like deciding when I am going to drop into a curve instead of the bike or tire doing it for me. I felt like I had more control over what the bike was doing and three 40k makes more sence to me. Also the occational rain groove or draw bridge gave a quiet easy ride a little dash of excitement. Eventually I will get close enough to a bike I consider a match for my '01 with a CT that has many many miles on it to ride behind it awhile and talk to the owner to be comfortable enough to change over. My problem now is too old and technelogically behind the times.Please take your time with your research Dan and give yourself time for all the parts to seat. I will be looking forward to your results.
Thanks for your time

[oldbikers]

I have only had my car tire for a short time and only about 400 miles but I agree that the tire in the video had to much air as my tire with 32psi has a slight bulge at the bottom and the one in the video had known, as for Dan I would hate to agree with anything he said but I have noticed some difference but nothing I am concerned about I will post again after a few thousand miles on the tire.

[flavor]

It shouldn't take bal##s to post something on this site. (As one person referenced). First off no one is in reach of being able to grab you by the throat and strangling the sh## out of you). But most of all this site is about camaraderie of riding and the Nomad being a common factor. I enjoy opinions from different perspectives, based on facts or not. I use the information as a reference. And as also mentioned, I also make my own decision in the end.

So don't be shy, just respectful. (As is almost always the case).

Now who's got the noose?????????????

[dantama]

I took some stills from my video slalom to see what the edge, flat, edge feeling looked like.


rear tire at speed leaned over




Front tire superimposed leaned at speed





Car tire outlined in yellow



As you can see, the weight and inertia flatten both tires out at the contact patch. Even the front tire has a flat spot for the contact patch, as I expected.

That flat spot rotates from side to side as you do a back and forth lean. So if you picture the red front tire superimposed image, that flat spot rotate around that curve, making a flat spot at each increment of lean from one side to the other. But it is always a flat spot that follows an arc. Think of rolling a water balloon from side to side on a counter top.

The car tire contact patch flat spot does not follow an arc. It deflects more of the edge than I realized, even with too much air in the tire. But because it does not follow an arc, the flat spot goes from the edge as shown in the picture, to flat across the tread upright, to the other edge and deflects that edge a lot once again.

I can feel when it goes from edge deflection, to flat across nearly the width of the tire at straight upright, to the other edge deflection.

I can't prove it yet, but I think that the bike tire contact patch stays the same size as it follows the arc of the bike tire. I think that the car tire contact patch gets larger on the straight up part as it spreads across the width of the tire because it is not an arc, then gets smaller as it rides up on the tire edge, deflecting the edge. But I doubt that on edge the contact patch is as wide as it is when the flat part of the tire is making the contact patch. I think on a back and forth lean, it would go from one side a little narrower, a little wider at straight up, to a little narrower on the other edge.

I'm certain that the bike tire contact patch smoothly follows and arc, and the car tire does not. I'll see what I can do as for as proof. More so than the preliminary stuff I posted here in the pictures. I know what I can feel on a bike, I just need to find a way to visual translate what I can feel. I'll get there.

[jandreu]

One of my concerns with a CT was the amount of contact when cornering. Both Dan's example and the video of the Goldwing show that while cornering the contact with the road is about the same for both tires. It makes sense to me that when in a straight line the CT would then have a wider contact than the MT which would translate into the reported handling benefits in braking and rain for the CT [although the better handling in rain I suspect is due to the tread design]. I can not see how a CT could maintain the same arch as a MT while in a straight line or during the transition from corner to corner, it simply is not made the same. This would then translate into Dan's feeling of corner-flat-corner.

I think everyone is correct in their respective "feel" of their own bike and this is one of the forums better discussions on the subject.

[pooker]

Originally Posted by Dan Lund

I took some stills from my video slalom to see what the edge, flat, edge feeling looked like.


rear tire at speed leaned over




Front tire superimposed leaned at speed





Car tire outlined in yellow



As you can see, the weight and inertia flatten both tires out at the contact patch. Even the front tire has a flat spot for the contact patch, as I expected.

That flat spot rotates from side to side as you do a back and forth lean. So if you picture the red front tire superimposed image, that flat spot rotate around that curve, making a flat spot at each increment of lean from one side to the other. But it is always a flat spot that follows an arc. Think of rolling a water balloon from side to side on a counter top.

The car tire contact patch flat spot does not follow an arc. It deflects more of the edge than I realized, even with too much air in the tire. But because it does not follow an arc, the flat spot goes from the edge as shown in the picture, to flat across the tread upright, to the other edge and deflects that edge a lot once again.

I can feel when it goes from edge deflection, to flat across nearly the width of the tire at straight upright, to the other edge deflection.

I can't prove it yet, but I think that the bike tire contact patch stays the same size as it follows the arc of the bike tire. I think that the car tire contact patch gets larger on the straight up part as it spreads across the width of the tire because it is not an arc, then gets smaller as it rides up on the tire edge, deflecting the edge. But I doubt that on edge the contact patch is as wide as it is when the flat part of the tire is making the contact patch. I think on a back and forth lean, it would go from one side a little narrower, a little wider at straight up, to a little narrower on the other edge.

I'm certain that the bike tire contact patch smoothly follows and arc, and the car tire does not. I'll see what I can do as for as proof. More so than the preliminary stuff I posted here in the pictures. I know what I can feel on a bike, I just need to find a way to visual translate what I can feel. I'll get there.

Those pics that you posted look like the tire has why too much air pressure!!!!!

[dantama]

Originally Posted by pooker

Those pics that you posted look like the tire has why too much air pressure!!!!!

Yup, as I said earlier, the installer put 39psi not 34. I'll lower it and have another go at it.

Here's what it looks like parked(not the same dynamics as when moving) as far as my thought experiment about the contact patch getting smaller and wider depending if on edge or straight up.

I've never had a physics class, but my intuitive seat of the pants physics is pretty accurate. I can climb bridges, ride bowls in skate parks etc. successfully first try becasue I think out in my head how all the forces will come together and what it will feel like on the bike as the bike interacts with it all.

I knew that I could feel the bike get up on one edge, then flatten out, then get up on the other edge. I also thought in my mind that the contact patch would get smaller as it did so, then get wider, then smaller.

The bike would have different forces at play at speed, but my parking lot slalom was at very low 1st gear speeds, not like leaned over at 60mph.

In these pictures, I left the camera sitting in the same spot, and the bike in the same spot. One pic is the bike on the side stand, then leaned onto a brick to get more lean, then straight up.

The bike didn't move in relationship to the camera, so you can put a business card or something up to the screen and measure how the contact patch moves wider and narrower.

Lots of lean



less lean



straight up


I put a bathroom scale under the side stand to see how much weight went on to it, then guessed how much more weight would go onto it leaned the thickness of the scale when it leaned more without the scale. Then straight up I took a bottle jack and a block and lifted that much weight off the bike at the same point front to back as the side stand, so that the same weight would be on the tire in each instance.

I don't know why some of you can't feel this happening while riding, but it does happen.

BTW, the thin piece of cardboard in the pic was used to move back and forth, front to back under the tire to see where the rubber was in contact with the ground, then I used the broom lines in the cement to bring it forward a few inches to put the white wrappers on the same broom line so that it would show up in the photos.

That's how I gauged the width of the contact patch.

[poppy]

Dan, as a prospective darksider, I appreciate your candor and honesty in this report. I have a fellow commuter who installed a CT on his 1700 Nomad and as he is still running the higher break-in pressure, I see exactly what you have shown.....riding on edge and flat during cornering transitions. Anyone who thinks that does not occur has obviously not followed a mc equipped with a CT with break-in pressure. It happens and no doubt you can feel it.

Anyway, I am about to order a 185/75/16 for my 1500 once I find a good source. I will keep an eye on your further observations and I have no doubt you will be forthright in your report, perhaps brutally honest!!

[Cajunrider]

Dan, Something you aren't putting in the equation is the centrifugal force that will flex the sidewall of the tire while moving through a curve. My tire is lifted toward the edge somewhat while on the side stand also. It's not the same as when the bike is moving. Comparing apples to oranges? Several riders on this forum have followed me in tight curves while I was leaning enough to drag my tailpipe extensions and floorboards and told me they observed the contact patch flat. They could see the sidewall bulging and flexing to keep the majority or all of the flat surface of the tire on the pavement. This is with 26 psi, not 39. I've followed two darksiders on this forum recently and observed the same and both were running a little over 30 psi in their tire. I've had physics in high school and college and wouldn't attempt to apply it to determine how much a tire flexes at different speeds and tire pressures. I'm sure an engineer could figure it out given tire construction data, weight of bike and rider, pavement camber, and the speed of the bike. It would require an engineering mind and plenty of time. What do you think ndbigfish?

[garyo4]

Alll great info here, I'll be following the results!

[dantama]

I agree Cajun, that's why I wrote it in my report with the photos. Though the picture of me leaned while in the Slalom showed the same thing with 39psi. I'll do it again with 32psi and see how it looks.

At 39psi and moving, it looked the same as in the pictures with it parked, but there are certainly other forces at play when moving, as I stated.