No, just a simple engineer thats picky about the use of words like "exact"
I too am an engineer…and the ONLY people who would NOT say that they are EXACTLY the same are theoretical scientists. When dealing with real-world engineering…they ARE the same.
you re just guessing now
again, if you did this test in a work truck with 1500 lbs of tools in the back, it would be more significant, we don t all have compact cars
you re just guessing now
You’re right…and since it’s probably impossible to figure out…and or measure…it’s insignificant.
Are they EXACTLY the same…NO…but in a real world situation they are…since it can’t be measured…or possibly even calculated. There’s just a theoretical model to explain there probably is a difference.
starman seems to be the kind of engineer who makes a structural steel fabrication job easy, there are others who don t
well he gave you the formula, im not an engineer but it seemed fairly straightforward and certainly not impossible.
since I have loaded a truck so heavy that the tires were much flattened and am sure the pressure difference could have been measured, I must disagree. many engineers don t have a clue about the real world. there is no point in going further tho so I ll just agree to disagree with you
well he gave you the formula, im not an engineer but it seemed fairly straightforward and certainly not impossible.
Yes there is a theoretical formula…but you need to be able to measure the deflection of the rubber compound. As I said…it’s probably very miniscule. So small in fact you probably need to carry the decimal places out 4 or 5 digits to have any difference.
Ever calculate the odds of winning the lottery? If you carry out the digits to 5 decimal places…the odds of winning the lottery are the same if you buy a ticket or not. Both would be 0.00000%. You need to go out to 9 decimal places to get anything but a 0. That’s why I never play the lottery.
I must disagree. many engineers don t have a clue about the real world.
If they don’t then how do they design anything in the real world?
im talking about the actual fabrication methods required to put some of their convoluted designs into practice I ve sent countless revisions back to engineering to get approved, and they always were, saving the company I worked for thousands of manhours. they just seemed like common sense to me.
other engineers are quite good, I m sure you fall into the latter category
of course the ones working for the car companies are having their troubles…
I will say that the most problematic of the engineers were Chinese. they seemed to have gotten their educations from a cracker jack box. from my experience the high numbers of engineers they are putting out are paper tigers. if we can ever protect our intellectual property we won t have much to fear from them innovation wise.
as far as measuring it , it does not seem impossible to me. put a tire in a tub of water, put weight on it , measure the displacement volume and run the formula. no?
as far as measuring it , it does not seem impossible to me. put a tire in a tub of water, put weight on it , measure the displacement volume and run the formula. no?
I don’t think so…because what starman is talking about is the compression of the rubber inside the tire. So the overall outside dimension shouldn’t change. But…if it does change…then placing in water is a very good and accurate of measuring it. But not sure.
I will say that the most problematic of the engineers were Chinese. they seemed to have gotten their educations from a cracker jack box.
I’ve worked with many Chinese and Indian engineers over the years…and they are extremely good. However there has been on occasions - language problems.
Just a couple of thoughts:
The difference between the pressure in an unloaded tire vs a loaded one? Depending on the load, but up to a half a psi. - and you can buy tire gauges that sensitive. But for that measurement, I used one more sensitive - nearest 0.1 psi.
Ideal Gas Law: PV = nRT. It’s an approximation that works quite well for pretty close to all gases in the range of pressures and temperature we humans ordinarily experience. Get into space or really pump up the pressure and the formula doesn’t work as well.
And, yes, there is a difference in the volume of the air chamber in a loaded tires (compared to an unloaded one). The loaded tire is a bit smaller.
one of the biggest problems I encountered with Chinese engineerswas their failure to see the big picture. I ll give one example.
let s say there were 100 welds on a particular structural pc. . instead of calculating the type and size of welds these connections required, they would just label them all as needing the strongest welds. this might save them 4 hrs, but it would cost the shop 100 extra hrs labor. and over welding members can make them weaker not stronger.
part of my job , as quality control supervisor, became going thru all the prints and pointing out the errors for revision.
before we had a quality control department, these welds were often just applied.
that s just one example of many.
After replacing the tires on my FWD Matrix I did the first rotation, front to back, at 5k and every 10k after that.
My reasoning is 5k miles after the 1st rotation the tires should be even front vs back, because they’ve all spent the same mileage in both positions.
So after another 5k the tires should have about the same tread difference as at the time of the 1st rotation.
I’m coming up on the 3rd rotation (25k total miles) and all seems well.
This will probably induce some screams of rage. I don’t rotate any more on my 2002 Sienna with more than 200,000 miles on it.
Yohohama warranty voids the minute I cross into Mexico. So rotating for warranty is not on the list at all.
I keep an eye on things, and don’t see anything wrong.
Last time I bought new tires, they examined the wear and they were so evenly worn they didn’t even recommend alignment. Car runs straight when you let go of the wheel on a flat, smooth road. And, this is after around 50,000 miles on Mexican roads. When I first came here, I hit a horrid road hazard and then had to replace a tire and have the front end aligned. No more.
I do not recommend this to any other driver. I have learned my car and my driving pattern. If something goes out of whack, I will be able to tell it easily.
If I get another car, I will probably start all over again, until I develop confidence again, just as I did with my 7800 mile oil changes with Mobil-1 EP and no snow zone driving. Another car may be totally different.
As far as Robert’s speed, I am told that people drive like that on the autobahn all the time.
As much as I hate to admit it, it looks like he is the expert on high speed Interstate driving here.
Some years ago, I had a scanner. The state HP was called to a wreck, He told where he was, and they asked ETA, He figured it at 120 mph, and that was not on Interstate, but on a 2 lane primary winding road at 2 am. I forget if Robert has red lights and siren or not. That will make a big difference in his safety with other cars around him.
As a very minor technical point, he said he doesn’t drive fast with cars around him, but told of driving at 105 and a Toyota was trying to pass him. That Toyota constituted a car close by him.
Ideally, I would always rotate the tires no matter what their mileage.
I just didn’t realize how many miles I drove since I personally rotated them.
Never thought of rotating every oil change - that’s now another burden.
My training in high speed driving, in a Barricuda, hardly applies to emergent transports in vehicles I drive gently.
See what is ahead before you get to it. Do not drive faster than you can see an object or pavement flaw and slow enough to go around it. Same with cresting an incline.
No speed on curves where it puts any appreciable lateral forces on the tires.
No speed through water causing hydroplanning.
No speeding at night where wildlife or cattle or horses on the road cannot be avoided. (Saw a moose a few nights ago! I was under the posted speed limit.)
It is amazing at how smooth the Expedition is at its governed 105 mph. (If unsafe, would Ford not govern it lower?)
Both are authorized emergencyehicles.
At 120 mph, the smooth Camry seemed as though it could easily go faster, but the Michelin tires are T rated = 118.
The hospital said, “Get the blood here as quickly as possible.” so I was not going to slow from 105 in lane 1 so the Corolla could pass me in lane 2. He easily could have because he caught up to me. He then suddenly dropped back… Wonder if he had a radar detector.
“As much as I hate to admit it, it looks like he is the expert on high speed Interstate driving here.”
I’m inclined to think Robert is NOT the expert in that regard
After all, some of our regulars were/are in law enforcement
Some of them probably were trained in high speed driving, and might have some interesting stories to tell us