mods for better mpg

[theholycow]

Originally Posted by cat0020

Different tire rubber/silica/material compound does not effect the contact patch size?

Well, the stiffness of the sidewall could have a small effect on contact patch...but not much.

[theclencher]

"The motorcycle tire will have to do a lot more flexing and deforming to make that contact patch, which would increase rolling resistance."

I think you are correct and IMHO chances are good the car tire has lower rr than the bike tire.

Bikes really don't coast well at all and I think it goes beyond the low weight and awful aero.

[cat0020]

I wonder how much of a difference the tire material would have in contact patch and rolling resistance.. would car tire have more rolling resistance because of thicker tread/stiffer carcas?
Seem to me unlikely that a Valkyrie would get better fuel efficiency with a car rear tire vs moto rear tire.

Originally Posted by theholycow

Tell me the weight on the tire and the pressure in the tire, I'll tell you the contact patch. I don't need to know the tire size.

Your statement seems to imply that no matter what size of tire, given the same weight carried on the tire and same air pressure in the tire, the contact patches would be the same on different tires... which seems to me grossly incorrect.

[theholycow]

Originally Posted by cat0020

I wonder how much of a difference the tire material would have in contact patch and rolling resistance.. would car tire have more rolling resistance because of thicker tread/stiffer carcas?
Seem to me unlikely that a Valkyrie would get better fuel efficiency with a car rear tire vs moto rear tire.

I don't know which tire would have less rolling resistance. The motorcycle tire may have to do more flexing because of its round profile, while the car tire may have thicker sidewalls.

How does one corner effectively when using a car tire on a motorcycle?

Your statement seems to imply that no matter what size of tire, given the same weight carried on the tire and same air pressure in the tire, the contact patches would be the same on different tires... which seems to me grossly incorrect.

The size would be the same. The shape would change.

[mikehallbackhoe]

as long as you are talking tires, I will join in, and hopefuly learn something. I can tell you this, the altima is one of the lightest tires out there, so I don't think there was any difference weight wise. definitely more tread on the ground, wouldn't probably work on a sport bike, but on a cruiser, you run out of clearance before you run out of tread. leaned all the way over, I still have about an inch of tread to spare. less tread on the ground leaned over of course, but still more than a motorcycle tire. don't think I gained any mpg with the car tire, but didn't lose any either. friend of mine went with a 65 series tire, and seems to be getting better mpg, possibly gearing? motorcycle tread compound is actually harder than a car tire, so much better traction with car tire. my motorcycle tires were wearing out between 5 and 6 thousand miles. at 200.00 a piece, it was getting kind of spendy. the car tire cost 100.00, and should last at least 20,000 miles. after trying both, the car tire is the more comfortable ride. currently running 36 psi. they call this riding on the darkside, if you want to google it.

[Jay2TheRescue]

Sounds interesting. Do you have any pics of your bike with car tires on it?

[mikehallbackhoe]

sorry, I have no pictures with the car tire. I would have to get my daughter or son in law to take a picture with their phone, and see if they could figure out how to post them.

[theholycow]

I wrote up detailed instructions for posting pictures. The writeup is on another forum; don't mind the rowdy, bawdy crowd there...
http://allofftopic.com/showthread.php?t=269

[mikehallbackhoe]

thanks, when my kids get back in town I will use their phone for a camera, and give it a try

[DarbyWalters]

Funny, greeted kinda poorly...left the forum...and now the discussion gets informative ;-)