Cayman Islands - Tire Pressure Issue

[RidingOnRailz]

I dutifully carry a tire gauge with me on vacation, so that I can check tires on whatever I'm driving there.

The car rental agent who signed off on the car I was to drive in Grand Cayman for 5 days says that he keeps all cars in his yard at 28psi, regardless of what the car or tire mfg says, for the following reason, and I quote:

"The ground and air temperature are so hot down here that it overheats the tires and warps the rims.."

Unquote.

So I took him at his word and drove off. Next morning, I checked the tires: all between 20-25PSI, on a 2005 Suzuki Swift requiring 33PSI front & rear!

I compromised, setting them to 30psi at a station two blocks away. Ride & handling was surely improved. I didn't set them all the way to 33 because I didn't want a letter or a phone call a week later from so&so rental car Grand Cayman that something happened to the wheels on the car I rented. LOL!

Your thoughts on this rental agent's SOP(standard operating procedures)?

[MagicRat]

Total nonsense.

I suspect he was trying to allow for the natural slight increase in tire pressure as a tire heats up during the day due to sunlight, driving etc. However, this only makes sense if he checks the tire pressure at dawn, when it's coolest.

Also, the Caymen Islands are no hotter than much of the US in the summertime... and nobody else experiences such problems. Rims do not warp due to heat or excess pressure, just severe impacts.

IMO if he has 'warped rims', its due to the abuse that many rental cars receive at the hands of people who simply don't care about the vehicle. (They don't call them "rent-a-racers for nothing )

As for tire pressure, I believe all cars have the manufacturers suggested tire pressure displayed somewhere on the vehicle... inside glove box, door post etc. This is a good starting point for a moderately-loaded vehicle. If it's loaded to the max, increase the tire pressure to the max shown on the tire sidewall.

[RidingOnRailz]

Originally Posted by MagicRat

Total nonsense.

I suspect he was trying to allow for the natural slight increase in tire pressure as a tire heats up during the day due to sunlight, driving etc. However, this only makes sense if he checks the tire pressure at dawn, when it's coolest.

Also, the Caymen Islands are no hotter than much of the US in the summertime... and nobody else experiences such problems. Rims do not warp due to heat or excess pressure, just severe impacts.

IMO if he has 'warped rims', its due to the abuse that many rental cars receive at the hands of people who simply don't care about the vehicle. (They don't call them "rent-a-racers for nothing )

As for tire pressure, I believe all cars have the manufacturers suggested tire pressure displayed somewhere on the vehicle... inside glove box, door post etc. This is a good starting point for a moderately-loaded vehicle. If it's loaded to the max, increase the tire pressure to the max shown on the tire sidewall.

Agreed, and thanks. Looks like both of us smelled a "rat"(pardon the pun! )

Another tire inflation tip I've heard in numerous quarters is to set the cold tire pressure so that tread-to-surface contact is equalized from center to shoulder. Most folks have told me this is usually above car mfg door sticker pressure but below the max pressure on the tire.

I.E.: A 2005 Impala may optimize its contact area at 32-33lbs(depending on brand/class of tire), even though GM specifies 30psi on that car IIRC.

[MagicRat]

Originally Posted by SmoothHandler

Another tire inflation tip I've heard in numerous quarters is to set the cold tire pressure so that tread-to-surface contact is equalized from center to shoulder. Most folks have told me this is usually above car mfg door sticker pressure but below the max pressure on the tire.

Theoretically, this makes sense because the tire pressure goes up slightly as the tire rolls along the pavement.... so the manufacturers reommendation would increase slightly to the ideal pressure...

Of course, the problem is the ideal pressure changes as the load on the car changes.... add another person..... fill the tank..... and the ideal changes.

However, one can experiment with placing a stripe across the tire tread using chalk then driving for a few minutes and then looking at the chalk.

If the chalk mark wears off the tire evenly, the pressure is ideal... if it wears off the center first, the tire is over inflated... wearing off near the edges means underinflation.