I did some checking since you seem so **** about "round per mile." I also saw you call it "rounds per mile." I did some Googling and couldn't find anything on these except for posts by you in various forums, where your arrogance blows just like it does here. Where people don't believe your crap any more than I do.

Anyway, to shorten the story, it's correctly called revolutions per mile. Please make a note of this. You won't look so stupid in the future if you do. Here's a couple of definitions I found at Tire Guides:

REVOLUTIONS PER MILE = Measured number of revolutions for a tire traveling one mile. This can vary with load and inflation.

ROLLING CIRCUMFERENCE = The linear distance traveled by a tire in one revolution. This can vary with load and inflation. Rolling circumference can be calculated as follows: 63,360 divided by revolutions per mile = rolling circumference in inches.

Can you figure out what my point is here, or do I have to explain it to you using baby words? I bolded some pertinent text, but you have to fill in some blanks about accuracy and variation in the real world. This shows your "rpm" theory, as you've been hawking it, is full of crap. It only works on paper.

BTW, did you do the test I suggested? What were the results?

 

You did Google search?!
WOW ! I am impressed.
Should have taken a 2-nd grader to help you and than you might get somewhere.
Than again, if you could understand English, you'd find in my first reply to look at manufacturers sites.
Here is Michelin Energy MXV4 data.
On page 2 in row 9 you'll find Revs/Mile data. Usually customers don't pay an attention to such detail data, till they have some kind of problem with mismatch.
BTW rpm shouldn't vary with load and inflation, because the driver suppose to adjust the inflation according to the load, to keep rpm steady.
http://www.michelinman.com/assets/pd...gymxv4plus.pdf

 

At this point, I don't think anyone is having a problem understanding this. You're the only one. We're talking about tires of differing sizes. thequif said his tires are a different diameter by one inch. You can't accept this because it blows your theory with a stench, so you just conveniently ignore that fact. Close your eyes and wish really hard and maybe all this truth will go away. You're not getting any further here with your BS than you are on the other forums.

You have a poor understanding of what the rpm is and how to use it. Michelin will tell you that load and inflation affect the rpm. We're talking about the real world here, not theoretical design numbers. Even you recognize that a driver "SHOULD" adjust inflation. That doesn't mean they will. When they don't, the rpm varies.

Your theory demands that every person exactly adjusts his tire pressure to match the rpm based on the weight of his car and the weight of the contents as they vary day-to-day. This is impossible, at best impractical. Your theory demands that everyone weigh their passengers and their cargo and adjusts their tire pressure accordingly. Then adjust again when you unload them. When you fill the gas tank you adjust the tire pressure. As the tank empties you adjust the tire pressure. It's clear that you do not understand how to use the rpm figures in the real world.

READ THIS CAREFULLY - You don't overinflate a smaller tire so it matches a taller tire's rpm, and tires of the same size vary in size by load and inflation.

My English? Yeah, right. If you didn't keep screwing up the expansion of the acronym rpm, then I could have shut you down a long time ago. There's no such thing as "round per mile" for tires. I not only have to deal with your idiocy, I have to deal with your mangling of the English language.

 

So you couldn't see row 9 on Michelin page?
Man!... You need to see a doctor.

 

Actually, I did. Row 9 on page 2.

I knew you were wrong on this. You're just being a knucklehead. I e-mailed Michelin and asked if the tire's rpm can be used to determine a tire's circumference. Hey, guess what? For some reason that I and everyone else can understand but you have yet to grasp, they don't agree with you. Here's the e-mail.

Thank you for visiting our Web site and sending us your e-mail.

Regarding your message:

<I need to determine the true circumference of my tires. Can I use the rpm
(revs per mile) value to do that while the tires are mounted on my car?


____________

We do not have a formula to calculate tire circumference. The easiest way
would be to measure the circumference with a tape measure.


If you have additional questions, please respond to this email
or you may call us at 1-800-847-3435 (toll-free) between
8:30AM and 6:00PM Eastern Time Monday through Friday to allow
one of our Consumer Relations Representatives to assist you.

Michelin North America
Consumer Relations Department

(Please Do Not Delete the line below.)
Email ID: 1481865

Regrettably, I didn't make clear that the tires would be on the car and loaded when I measured them. I believe they assumed I would lift the car or remove the tires before measuring them. In any case, this still blows your theory to poop, don't it? Why didn't they just tell me to divide 63,360 by the tire's rpm like you keep saying?

Remember when I showed you the following formula?

ROLLING CIRCUMFERENCE = The linear distance traveled by a tire in one revolution. This can vary with load and inflation. Rolling circumference can be calculated as follows: 63,360 divided by revolutions per mile = rolling circumference in inches.

Why didn't they give this formula to me? The answer is because it doesn't apply to real world measurements. I told them I wanted the true circumference. Or, do your relatives work at Michelin and are giving out bad info? Is that what you're going to claim next?

 

"true circumference" ? What da heck is that? Something that evidently even experts from Michelin know nothing about. Are you hallucinating again?
Man, you need to see a shrink as well.

 

Sorry, but you can't BS your way out of this one. You AND your rpm theory are debunked. Time to work on some other bad info you can try to pass along.

Thank you. Please drive through.

 

the above was very interesting.....that is all

 

Assuming the tire tread does not slip in the axis of roll, the rolling diameter will be the same whatever the low pressure or weight on the tire. If the tire is over inflated significantly there may be a slight increase in rolling diameter but I can't see there being much stretch allowed in the belts below the tread.

I am trying to match front tires with rear 305x40R18's and am wondering what % difference in diameter F-R the stability control systems will allow.

 

I did this on my 95 e320 wagon-- ABS system applied the brakes for 30 miles before I realized why the car seemed sluggish.