I've got a question and a tale of woe...

(2004 RX-8, 6-Speed, OE Dunlop SP Sport 8090 [225/45/WR18])

This morning I went to (what I had previously thought was) a reputable tire service center to have a slow leak repaired on my right front tire. On the way home, the tire pressure monitoring system lit up. When I got home, I found the tire's pressure was 54 lbs! (Owner's manual specification is 32 lbs, cold.)

I also found the valve stem cap and the wheel hub (with the Mazda logo) missing.

Called the center. Received a boatload of attitude. No apology for the missing parts, just a suggestion to come back and they'd look around for them. Got them to find the parts before I returned.

More important was their answer regarding the pressure. Their policy is to inflate all tires to the value shown on the sidewall (51 lbs on these tires -- the difference in the value I read was chalked up to a lousy gauge on my part; couldn't be theirs). I told them my understanding was that value ("Maximum Inflation Pressure") was the highest the tire could safely withstand, and not the value it should be set to. They disagreed. They felt Mazda's value was way too low.

I checked the US DOT website, which says, in part:

Manufacturers of passenger vehicles and light trucks determine this number based on the vehicle's design load limit, that is, the greatest amount of weight a vehicle can safely carry and the vehicle's tire size. The proper tire pressure for your vehicle is referred to as the "recommended cold inflation pressure."

Because tires are designed to be used on more than one type of vehicle, tire manufacturers list the "maximum permissible inflation pressure" on the tire sidewall. This number is the greatest amount of air pressure that should ever be put in the tire under normal driving conditions.

Went back to the center and had a talk with the boss of the day. When I mentioned the DOT's recommendation, he told me the "DOT has its own agenda, which does not necessarily match ours. We aim to provide a safe tire installation." His center sets tire pressure to the value the tire manufacturer puts on the sidewall, not to the value the car manufacturer specifies. After all, he told me, the Ford Explorer/Bridgestone-Firestone overturning problem was caused by too-low tire pressure specified by Ford.

We parted on not-friendly terms. I told him he'd treated me shabbily and had lost himself a customer for good. He wasn't impressed.

Now the question: who's all wet here, him or me? Anyone authoritative (such as Tire Rack) who can tell me these guys are endangering their customers?

Thanks,

Bob

 

What was the name of the tire center? Was it a national chain?

Other than that, just let the tire pressure out of your car and never go there again.

 

Regional chain (of two centers) in southeastern Massachusetts. I'll keep the name to myself for now until I'm convinced I'm right.

Naturally I let the pressure out right away. However, I'm concerned for other customers driving down the road with dangerously over-inflated tires.

On second thought, I guess it really is all about me! I'd hate to get creamed by one of their customers whose tire just blew out.

Bob

 

they are freaking dumb!!

 

You are the correct one in this case. Tire pressure should be set to what the manufacturer recommends, not the max tire pressure on the sidewall. That's an excellent way to get a blowout. These people are wrong and stupid and if that is what they are doing to all of their customers then the public needs to know. What they are doing is extremely dangerous.

 

How Not to run a business in deed. The door pillar placard inflation rating, or a bit more, but never the sidewall rating.

Under inflation is more dangerous than over, but this is absurd.

 

The only time I've ever used the sidewall rating was for autocrossing my Passat with 205/60/15 tires (stupid roll-over). But yah, for the street, that's not appropriate.

One of the guys I race with just got a GTO and he runs 50f/60r on tires that specify a max of 50psi (+/-). We are waiting for him to have a blow-out on the track.

 

I don't know about you guys, but when I first got my car, I didn't know the tires were over-inflated. When I finally checked at around 500 miles, it was at around 42 psi. Talk about over the max tire pressure on the sidewall, LOL!

 

Most sport tires should be inflated into at least the high 30's. Optimum traction for many tires is about 38-44psi (when hot at operating temp).

 

You are correct..now..WHO was it?

 

Yes I agree. The tire pressure should be set in a fashion that when reaching temperature they are at or below the limit.

You are right and i'm a professional. At least i think so. hehe.

We typically set tire pressure on high performance tires to about 36 cold. Should get up to 40 under normal driving conditions. If racing the best way to determine tire inflation and alignment settings for a particular track or venue is to use a pyro. Measure the inside and outside temps, and try to get them to match up by adjusting pressure and alignment within certain ranges of limitation.

alright now, tell us who it is. I think this guy been breathing rubbing alcohol from balancing wheels too much.

Honestly the best thing would be to call your tire manufacturer and ask their technical service rep the question. I doubt they would spend the time, but imagine the Tire Manuf rep contacting the owner and giving them a piece of good "info".

 

Sounds like I would NEVER return to that tire dealer! Don't know nothing about tires and car manufactuar inflation pressures.
The guy has been snorting to much sheep dip.

 

How does he justify running that much pressure? Does check roll-over?

More importantly, does he beat your times?

 

So who was it? anyone big like discout tires?

 

Hmmm... I wonder why tire shops do this...

As a matter of fact, I went to my local Mazda dealership to get an oil change a couple of days ago, and they topped off the pressure in my tires...

When I checked them the next day (cold), they were reading between 44 to 46 psi...
....strange....(Maximum pressure for Dunlop's is 51psi)

I guess I don't really care as I officially parked my car yesterday for the winter. Over inflation will help the tires while the car sits for a couple of months...

 

That's crazy.

I guess they're applying highway speed limit logic to tires. If 70 mph is the limit, you should be driving at LEAST that speed

I maintain my tires @ 34 psi cold.

 

Wow.. not good! I would contact the manufacturer as well as the Better Business Bureau.

 

most people do know what amount to put in there tires some do not i think the state police would like to have a few words with this guy because you think about the amount of accidents that happen and no one checked the tires or lived to tell the story.this affects all of us good drivers or bad.a blow out tire has no aim for where it hits or takes out.a blown tire is like a drunk driver you never know where they all are but once you are hit it's too late.be very carful who you let touch your car because once your gone ...your gone!!