Is my mechanic stupid?

[cpals]

I know there's been a few posts on this before, but nothing in particular to this.

I got my oil changed at my local mechanic's shop and he checked my tires and they were a little low. So I asked him what PSI I should make my tires and he said to use whatever was on the tires since they "know better about their tires than anyone else."

I've heard many things about psi and what numbers to go by and such, but thought his recommendation was a bit high (the numbers on the tire said 44psi). I think my car door says something like 35-38.

Am I driving around with tires that could pop since they are at 44psi?

 

[minendo]

Are they the stock tires provided with the car?

 

[shuan24]

i dont think so dude. I would think you're tires should know what PSI to be at, not your car door.

 

[isekii]

I think the 44 psi is under max load ?

 

[Kalvin00]

If the tire says recommened is to run at 44 psi, do it.

 

[NutBucket]

Originally posted by: isekii
I think the 44 psi is under max load ?

44 is max pressure. Follow the car door. For example, my 17's say max pressure is 44psi. I run them at about 32 or so.

 

[cpals]

I don't know if they're stock or not since I didn't buy the car new. They're Goodyear Conquest tires. Side of tire says 44psi Max Pressure.

 

[Quixfire]

Follow the listing on your car door as long as the tires are the specified size listed on the label. Your mechanic is wrong to think that the tire manufacture would know better than the vehicle manufacture. Tire maker make one size tire, P235/60R15 for example, to those specification. They do not make tires to fit a specific make or model.

 

[captains]

i always go on whats on the tire then adjust accordingly.....if they are 35 i put 32....if they are 44 i put 40

 

[Viperoni]

Though this has been discussed MANY times....

The 44psi is a MAXIMUM pressure limit set by the tire manufacturer. It's only used when you're carrying a super heavy load (such as towing), and a few other circumstances (one being speed: my michelin's need more air pressure to safely maintain a higher speed).

The manufacturers rating on the door takes into account the vehicle weight and comfort requirements, and bases their rating on those two factors, amoung many others, such as contact patch shape, etc.

So yes, your mechanic doesn't know much about tires. Follow the guideline on the car's door.

 

[WinkOsmosis]

The number on the tire has nothing to do with what it should be. PSI requirement varies with car. Why would your mechanic be dumb enough to think that every car that you put that tire on is going to work with that pressure?

 

[Wingznut]

<--- Ex ASE Master Mechanic of 10+ years...

Nutbucket, Quixfire, Viperoni, WinkOsmosis are all correct. Go with what your car says, not the max pressure on the tire.

 

[Tipe2]

Quixfire and Wingznut are correct, always follow the tire inflation placard either on your glove box door (old vehicles) or on your drivers door sill (newer vehicles).

The inflation pressure on the tire is the maximum inflation allowed by the tire manufacturer.


Yes, your mechanic is stupid.

 

[dabuddha]

Originally posted by: shuan24
i dont think so dude. I would think you're tires should know what PSI to be at, not your car door.

I think he should ask his Air Conditioner to make sure.

 

[Shockwave]

I run just under max PSI of the tire rating.
Ride quality be damned! I want performance and gas milage

 

[rh71]

I never knew the tire puts a recommended PSI on there.. only the max PSI.

 

[flyfish]

Take a piece of chalk and draw a line across the tire tread. Drive a SHORT distance down a dry straight road. If the chalk is line is rubbed off evenly, the tire pressure is correct for the vehicle. If it is rubbed off only on the edges, add air. If it is rubbed off only in the middle, let out some air.

 

[amndouglas]

Originally posted by: Shockwave
I run just under max PSI of the tire rating.
Ride quality be damned! I want performance and gas milage

Me too. Even though your odometer won't tell you, the gas mileage is better compared to underinflated tires.

 

[Pepsi90919]

find a new mechanic

 

[night]

yes the door rating. most ppl dont even know its there.

and another huge myth though is that the ones that do know that sticker is there think that the weight rating is how much the car wieghs. which its not. its the max rating caring capacity with a full load of passengers and trunk.

 

[Nocturnal]

If he suggested putting 45psi into a 45psi rated tire he is nuts. My tires are rated for 45psi and I put in 30psi max.

 

[bernse]

Originally posted by: flyfish
Take a piece of chalk and draw a line across the tire tread. Drive a SHORT distance down a dry straight road. If the chalk is line is rubbed off evenly, the tire pressure is correct for the vehicle. If it is rubbed off only on the edges, add air. If it is rubbed off only in the middle, let out some air.

I understand what you are getting at, but thats a new one one me.

Do you realize how much pressure you'd need to add to your tires to make them noticeably "bulge" in the middle? Or how low they'd have to be to only wear on the outsides?

Don't trust this measurement technique. For cripes sakes, buy a $1 pressure gauge!

 

[Murphyrulez]

Originally posted by: dabuddha

Originally posted by: shuan24
i dont think so dude. I would think you're tires should know what PSI to be at, not your car door.

I think he should ask his Air Conditioner to make sure.

I'm sorry, but I snorted.

 

[Murphyrulez]

Originally posted by: bernse

Originally posted by: flyfish
Take a piece of chalk and draw a line across the tire tread. Drive a SHORT distance down a dry straight road. If the chalk is line is rubbed off evenly, the tire pressure is correct for the vehicle. If it is rubbed off only on the edges, add air. If it is rubbed off only in the middle, let out some air.

I understand what you are getting at, but thats a new one one me.

Do you realize how much pressure you'd need to add to your tires to make them noticeably "bulge" in the middle? Or how low they'd have to be to only wear on the outsides?

Don't trust this measurement technique. For cripes sakes, buy a $1 pressure gauge!

It sucks when he fills his tires at the gas station, he has to keep backing up, driving forward, backing up, driving forward...

 

[Zenmervolt]

Originally posted by: shuan24
i dont think so dude. I would think you're tires should know what PSI to be at, not your car door.

Wrong.

The pressure listed on the tire sidewall is only the maximum cold tire pressure (also the pressure for maximum tire load). The recommended pressure is fine for the vehicle load limitations and it is what the suspension has been set up for. If you have a light car and tires that can carry more load than the car, then inflating the tires to the maximum pressure will cause the tires to be over-inflated for the application and they will wear poorly as well as provide severely sub-standard traction.

ZV