Prius Tire Tuning

Thanks for the explanation. This is still very new to me. (9_9)

The question was, where are your data concerning braking distance?

Oh--you have decided that data are unimportant.

You keep thinking that, Bob. You keep right on thinking that.

Meanwhile, we'll all get together on public record that you don't think actual data are required, that "it works fine" suffices for your declarations to the world.

I have to write, Elmo, that Bob has been leading you by the nose for at least a month now. Isn't it enough that you make a fool of yourself, much let others make a fool of you?

On May 22, 8:42 am, "Elmo P. Shagnasty" wrote: . . .

It has been more than fun and an example of how to train a troll. Your profile used to automatically delete postings after a week. Now you've turned it off so the record remains. This means the nasty crap you used to post is unlikely to return. Key to ending that bad habit is to not quote your crap or better still ... 'enhance it.' Regardless, you are finally taking responsibility and this is a good start.

Straw-men postings were and are simply replied with facts and data. Instead of going down the rat-hole, use them to bring what the troll lacks, fact based information . . . a teaching moment. As for arguing nonsense, again, use each opportunity to bring reality, the facts and data. So let's go back to Physics 101.

The larger diameter tires increase the polar moment of inertia. This is the gyroscopic force that tends to hold a rotating mass steady. Sad to say, the NHW11 steering geometry makes the car all but neutral even with perfect, four wheel alignment. So increasing the tire diameter converts the front wheels into more powerful gyroscopes which improves straight-line tracking.

So the next challenge is to find the largest, 14", low rolling resistance tire that can fit on an NHW11. That turns out to be the

The larger diameter reduces maximum acceleration. But efficient driving doesn't use maximum acceleration so this is not missed. However, there is a risk that the brakes might not be able to keep up. Fortunately, there is a maximum brake test, engage the ABS.

ABS works by sensing when the wheel is about to stop turning because the brakes have enough power to lock them up. If the ABS failed to engage, then the larger diameter tires would have exceeded the braking power and be unsafe. So one of my first tests was a maximum brake effort and sure enough the ABS worked.

Measuring stopping distance without having some reference makes no sense. The Prius is not sold with a stopping distance specification. Even after replacing the OEM tires, again, there is no standard for stopping distance since it is really a function of the tires. That the ABS engages is enough and the National Highway Traffic Safety Administration said as much in "DOT HS 811 182":

". . . As long as the driver maintains firm pressure on the brake pedal, ABS will automatically modulate the pressure at the wheels at a level close to the optimum braking force short of lockup. . . ." (pp.

In fact, here is a stopping distance calculator and tire and wheel diameter are not part of the inputs:

The ABS is activated by wheel rotation stopping or slowing down, not the diameter of the tire. As long as the ABS is working, stopping distance is not brake limited but a simple function of the tire tread, compound, and road surface ... the coefficient of friction.

See, this how to train a troll. Get them to take responsibility and always use their nonsense postings for a 'teaching moment.'

Bob Wilson

I ask you again: what "profile" are you talking about?

The record is clear: you're a wacko. The record gets clearer every time you say something.

What "nasty crap" is that, bob?

Ah, you not only announce that you're a wacko, you announce it with PRIDE. Facts are yours to twist to your own desire, eh, bob? "Enhance it"? You're not above out-and-out lying, and you've proven that every time you post.

Tell us again how you don't have to have any data or facts regarding braking performance on different size tires--that all that matters is "it brakes fine" and/or "I let the ABS handle it".

You are saying that "it brakes fine" is a suitable substitute for actual data. Again, every time you post something, you show what a wacko you are.

Did you really say that? Well, of course you did--you're an absolute wacko.

Measuring stopping distance of one tire against another is absolutely meaningful, and it's how the REAL world does things. But in your fantasy world, you decide you can do anything you want and declare it to be real and factual.

You're a wacko.

Yes, the stopping distance is a function of the tires. And the ABS will modulate the brake pressure at the wheels at a level close to the optimum braking force FOR THE TIRE THAT'S INSTALLED--that is, the ABS will not allow even the slickest and least sticky of tires to lock up.

What will happen is that braking distance will change based on the tire itself, because as you say "stopping distance is a function of the tires".

So if "stopping distance is a function of the tires" then why don't you care what affect a different tire would have on stopping distance? Why do you put on a different size/model tire and declare it to be satisfaction simply because "the car stopped"?

That's what this all started with: your own declaration that you saw no need to measure braking distance with the different sizes of tires, simply because you "let the ABS do its thing". You apparently don't even know the physics behind all of this, and/or are trying to flummox the public--who, as you can see with Al Falfa, is full of ignorant people--into thinking that your fantasy world has any basis in reality.

The NHTSA never said "that the ABS engages is enough". You created those words out of thin air, and then had the gall to quote a complete non sequitur.

ABS most certainly will keep ANY wheel from locking up, because the purpose of ABS is to maximize braking and control--and that is done solely by keeping the tire on the edge of locking up, without actually locking up.

But ABS has nothing to do with braking DISTANCE; as you yourself said, that's a function of the TIRE.

You don't have a clue, but you sure do like to act as if you do. And then you strut around proudly because you've gotten other ignorant people to follow you, the blind leading the blind.

The evidence is in the thread "Prius Power - 112 hours, 8 gallons" where your silliness has faded in to obscurity . . . except for the quotes. You are such a tool.

See that it doesn't and we'll all be happy.

Oh so soon, the troll mumbles "wacko" but then that is the way of a sociopath.

Again, the mark of a sociopath who substitutes personal attack for facts and data.

Fortunately, physics doesn't care for the claims of sociopath.

So instead of citing some stopping distance, just more ramblings of a sociopath.

Well it has been a long and nasty road but eventually you are coming around the how the real world works.

Fortunately Consumer Reports has already quantified Sumitomo T4 stopping using their 1-5 scale: 4/5 - dry pavement.

Exactly! The ABS normalizes any tire to stop as quickly as that tire is capable.

Again, physics and the natural world don't care about the utter nonsense of a sociopath.

Amazing, watching a sociopath try to make sense in the natural world.

Actually, it is just the sane dealing with a sociopath, a cornered one at that.

You are so my bitch.

Bob Wilson

wow, Consumer Reports. Is THAT the data you use for your pretty charts and graphs??

And you say it so proudly.

...and from that you declared that there's no difference in braking distance between tires, AND no need to bother to measure it.

And then when pushed, your idea of measuring it is...a Consumer Reports rating of the tire from 1 to 5.

This has all been FASCINATING, bob. It sure puts your pretty charts and graphs into the proper perspective.

. . .

It has and remains a useful exercise. Not only do we get to discuss Prius tire tuning but also learned about "The Tire Society," a new source of credible research papers. It is also shows how a troll's posting can introduce additional technical content. Simply treat their nonsense with ellipsis and thank them: 'Elmo' is so my bitch.

Based upon tire revs per mile and load, here is how the Sumitomo 14" tires, all rated at 51 psi maximum sidewall versus the 44 psi, OEM tire:

Looking at the list, the most interesting testing combination would be:

This would allow us to compare and contrast the smallest to largest diameter tire. We already know the larger diameter tires improve straight-line handling over the 175/65R14. But I just reviewed the definition of caster angle:

"The pivot points of the steering are angled such that a line drawn through them intersects the road surface slightly ahead of the contact point of the wheel. The purpose of this is to provide a degree of self- centering for the steering - the wheel casters around so as to trail behind the axis of steering. This makes a car easier to drive and improves its directional stability (reducing its tendency to wander). Excessive caster angle will make the steering heavier and less responsive, although, in racing, large caster angles are used to improve camber gain in cornering. . . ." - Wikipedia

One of the effects of a larger diameter is to move the road surface intersection further in front of the tire contact patch and increases the effective caster. So in addition to the higher gyroscopic forces, caster is also increased, a two-for-one advantage.

Given the different revs/mile of the Sumitomo 14" tires, there are different degrees of handling. For those who want maximum stability,

Bob Wilson

In fact, it has resulted in multiple postings in a number of different forums of this latest summary in multiple, moderated forums. This is why practicing with a troll can be beneficial. Even a sociopath gives us an opportunity to tune and tweak our essays into more than the original.

Bob Wilson

You keep thinking that, bob. In your little world, what color is the sky?

Still waiting for that data from you on braking distance--data other than "well, I think it braked just fine, therefore that's the end of it."

You keep thinking that, bob. In your little world, what color is the sky?

Still waiting for that data from you on braking distance--data other than "well, I think it braked just fine, therefore that's the end of it."

Since you seem to be stuck on this point, why don't you do a little of your own research instead of making a fool out of yourself by denigrating others?

Braking distance measurement would tell us something about the tire- road coefficient of friction and nothing else.

Bob Wilson

On May 23, 3:43 pm, "Elmo P. Shagnasty" wrote: . . .

If you want to hire me to measure the stopping distance, no problem. My standard rate is $50/hour, minimum of four hours. Send your paypal payment to:

snipped-for-privacy@gmail.com

Bob Wilson

Tell us all, bob, why I would want to hire you to provide data for your own claims.

Tell us all, bob, why you won't provide your own data to back up your own claims.

You say that as if it's meaningless, yet your claim was that changing tires "made no difference in braking".

Keep it coming, bob. You apparently love living in the holes you dig for yourself.

Ok, then hire someone else:

You might hire me because I'll give you options and some discounts. So there are three approaches: Good, Fast, and Cheap.

CHEAP o One maximum braking effort at an indicated, 35 mph, with the data recorded by an accelerometer o Reduction of data to give the braking distance

FAST o Toyota brake job with the charges pro-rated by unused brake pad/shoe material o Six maximum braking efforts at an indicated, 35 mph, recorded with half in each direction o Reduction of data to give the braking distance o Toss the highest and lowest and average the remaining four

GOOD o Everything above but using the following sets Sumitomo tires on the front:

Of course you would trust my results, right? Would you trust any of my results? As pointed out before, you have an interesting paradox:

- calling for me to do a brake study

- suggesting that my results are suspect

If you want a brake study, I'm willing for a fee to conduct one. But it won't be done for free as the time, energy and expense is not trivial. Let's see the color of your money as you are so my bitch.

Bob Wilson

no, YOU hire someone else.

If YOU want to make claims about performance, then YOU back them up. It's not up to the rest of the world to back up YOUR claims.

You act as if simply because you say something, it must be taken at face value--when nothing can be further from the truth.

You're happy to provide data that YOU like, while pointedly ignoring data that you DON'T like--and then try to make that the rest of the world's problem.

That's not how it works. If you want to claim "no difference in braking" then you have to provide data.

It was even funnier to watch you try to come across as erudite by saying that "it braked fine" and "I let the ABS work, so it brakes fine".

Why? I already know the brakes and tires are working perfectly fine. I thought you had questions.

I have but it sounds like there is only one FUD spreader who lacks the will, means or intellect to come up with anything of merit. If you have some facts and data, trot them out.

Now if you need to hire expertise, no problem and I don't care if you use a 3d party or hire me. Just the real world doesn't support freeloaders and parasites.

Well that is a lie as I've already referenced several sources and the braking distance URL showing exactly what happens. I've bring outside, credible sources and so far, the only one making unsubstantiated claims is you.

Fortunately you are not "the world" unless your parent played a cruel joke on your birth certificate . . . 'Elmo.'

Actually, I have brought both an NHTSA paper and a URLs discussing the stopping distance physics with a calculator. I've also verified the ABS works and the car stops as it did before. Still, we can start with basic physics.

Will this be with or without calculus? By that, do you understand what an integral is and how they are derived? Integral calculus means we don't have to teach you how to use a spreadsheet to handle piece-wise integration.

You are easy to amuse and my bitch.

Bob Wilson

. . .

Do you have a car with ABS brakes? What size tires? What make and model?

it should be fairly easy to do the experiment yourself and bring the results here.

Bob Wilson

well, Bob, I wasn't the one making the claims. YOU made the claims.

And you continue to insist that you have no responsibility to back up the very claims that YOU made.

You continue to insist that "I let the ABS work and it braked fine, therefore I had no need to test the braking performance" is actual data.