Super Hans wrote:I have no idea about the max pressure of the tyres you have specified, but sometimes tyre brands supply the information on the wall of the tyre.
In Taiwan, I wouldn't go anywhere near maximum pressures due to heat expansion in the summer (and therefore the risk of catastrophic failure) and less resistance to punctures. Also, and you already know all this of course, less of the tread is in contact with the road. They also wear down more quickly as they take longer to warm up if they are inflated too much.
I think any money you save on fuel consumption would be spent on increased tyre wear and increased suspension and steering wear.
jaame wrote:I'm no expert but 50 psi sounds miles too high for car tyres to me. I have always believed that they should be between 28 and 33, maybe 35 if the boot if full of something heavy. Every car I've ever had has had the tyre pressures in the owner's manual. I've always stuck to that myself.
Hi Super Hans. Thanks for your reply.
I think (provided one is within the maximum specified by the manufacturer, which I don't know, which is not moulded on the sidewall, and which a zero-zhongwen web search has so far not revealed) that internal heating, and consequent catastrophic failure is much more likely with underinflated tyres.
As you point out yourself, "they take longer to warm up if they are inflated too much." I think your implied statement that cold tyres wear more rapidly is questionable, but its likely that over-inflated tyres will wear more unevenly, as mine apparently have.
I think you're right that they're likely to be more vulnerable to punctures. I can live with that, partly because I havn't had any, and also because puncture repair is dirt cheap here.
As I said, wear on these tyres doesn't matter much, since they are at or approaching end-of-life.
The Redwagon link above gives a method of optimising the tyre pressure/footprint which should more or less address these issues, so I'll try that, but it would be nice to know what the safe upper limit was.
I sent an email via Bridgstones US website (telling a few automated lies filling in inapplicable obligatory fields) but they'll probably ignore it
Super Hans wrote:
My point was that if you inflate to the manufacturer's maximum recommended pressure, I'm not sure whether this would account for further expansion due to environmental factors such as outside air temperature, outside air pressure, road surface temperature, heat from breaking and heat from friction, or whether the maximum pressure includes all of these possibilities. What I mean is would 50psi be a safe pressure to inflate to, or would 50psi be the maximum pressure the tyre has been rated for?
Super Hans wrote:Ah - I see what you mean now. They're actually deteriorating, not wearing down.
Super Hans wrote:
You're incredibly lucky. I've just had to fix a slow. Last year, or the year before, I had a stick enter through the side of the wall.
Super Hans wrote:Ha. Good luck with that, but if you get any feedback, I'd like to know what they say. I've just forked out on a couple of Bridgestones for the rear, and will be purchasing the front lot next week.
thirdstring wrote:I worked at a repair shop before, and we had people coming in over 80 psi! That was the highest my gauge went. Definitely don't recommend that.
Actually, at least in the States, each vehicle determines proper tire pressure. On US cars, the recommended pressure for correct performance (handling, braking, fuel economy) is posted on the door pillar with a lot of other info. I don't know if Taiwan requires those labels or not, but you can find the recommended pressure in the owners manual I'm sure.
As for actual max pressure for typical tires themselves, 35 psi is most common, while some are 44 psi. "Cold" doesn't need to be cold weather, just don't come off the highway & set it at that pressure. Don't worry about them over-pressurizing due to various factors if you set it at 35 psi. I'm sure the burst pressure is at least 4 times the rated amount, and you're not going to heat it hot enough to get close to that.
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