Talking to a Bridgestone engineer tomorrow - got questions?

[SVOboy]

Just like the title says. Lemme know if you want me to ask anything in specific.

[Frank Lee]

I have some:

1. I was really happy with the OEM tires on one of my Fords, yet when it came time to replace them they were UNAVAILABLE to anyone but OEMs.

I have been relatively disappointed in my subsequent replacement selections.

I have since learned that oftentimes OEM tires are NOT available as replacements. The OEM tires often (always?) have better r.r. than what the tire shopper can get.

Why not fix this absurdity?

2. Is optimal contact patch geometry for lowest r.r. "square" i.e. same width as length? If my observations are correct, typical OEM tire sizing results in patches that are longer than wide. If the above postulate is true, would skinnier tires actually make r.r. worse?

3. What would your professional advice be to the serious hypermiler who wants to reduce r.r.? Is there a difference between "on the record" advice and "off the record"?

[Concrete]

Since tire design appears to be a trade between traction, wear and rolling resistance
why is the customer only given two of the critical components to chose tires?
Would Bridgestone have any plans to list rolling resistance?
I personally could find myself loyal to a manufacture that supplied all the data, instead of having to dig thru incomplete third party data & trying to guess what tire is lower RR.

Also
Does Bridgestone have plans for any higher pressures passenger tires?
once again I would be interested in becoming a customer of such a company.

Besides a look around your local store parking lot will show many tires designed to be in the 32-35 psi range - are living a life of dangerous under-inflation.
there is not much room when you are in the low thirties before you are building up heat in a tire and getting a blow out, or wallowing the bead off the rim. I seems like the tire makers would be pushing another 5 or 10 more psi for for safety - as well as being eco-friendly & saving gas.

best wishes on the interview

edit:
crap!
well I guess this is tomorrow

So how did the interview go?

[SVOboy]

The interview is at 10:30, to in about 10 hours, no worries

[orange4boy]

I have a couple, if you have time.

What is the safety margin or burst pressure in a typical passenger car tire? 50% of max sidewall? 200%? Is there a regulation on this (like in aviation) or is it an "industry self regulation" issue?

Roughly how high is the pressure spike when a tire is under full deflection like when hitting a curb.

I second Frank's OEM tire frustration and Concrete's LRR rating point.

Thanks.

[vtec-e]

All of the above and don't come back empty handed!!

ollie

[tasdrouille]

Originally Posted by orange4boy

Roughly how high is the pressure spike when a tire is under full deflection like when hitting a curb.

You can go with a worst case scenario using the perfect gas law and an approximation of the volume being reduced by the curb. We're looking at a 10% spike at most.

[SVOboy]

Originally Posted by tasdrouille

You can go with a worst case scenario using the perfect gas law and an approximation of the volume being reduced by the curb. We're looking at a 10% spike at most.

Hardly need to talk to anyone specific when we've got you around

[tasdrouille]

You should add "I think that" before anything I write, and end it with "but I could be completely wrong".

[RobertSmalls]

That would be a good first approximation if the pressure throughout the tire were uniform. However, it takes time for the pressure spike from the curb/pothole impact to reach the far side of the tire. Locally, the pressure could be quite high. Suppose I could tell you it's >200 psi for 0.05s. Is that enough to burst a tire or unseat the tire from the rim? Dunno, but as an engineer, I would recommend you close your eyes and ignore the pressure vs. time vs. position question, and pay attention only to the outcome. i.e. instead ask "To what cold PSI can I inflate a tire and still hit a pothole at 75mph without tire failure?"