Question about tires?

[Davescort97]

I recently ordered some tires for my Escort online. They didn't have the Continentals I wanted but referred me to some cheaper tires. What do these tires numbers mean? The number on the sidewall is 185/65 R14 82H VTQG 500 A-A for the Continentals and the numbers for the cheaper tires was 185/65 R14 82H VTQG 280 A-A for some Doral SDL all season radials. The maximum load limit on the Doral SDL tires is 1450 lbs at 57 psi. Wouldn't it be dangerous to run tires at 57 psi? What pressure should I run in them? The pressure is listed as 32psi. on a sticker on my door post. I know next to nothing about tires. Thanks Guys.

[Davescort97]

I did some checking. The 185 is the width of the tread in millimeters. 60 means the height of the sidewall is 60% of the tread width. The R means it is a radial tire and the 14 is the diameter of the rim in inches. The UTOG means universal tire grade. The 82 is the load factor and the H means it has a speed rating of 135. The 280 is the tread wear factor and denotes a tread life of 28,000 miles. The A A is the temperature rating of the tire. The Doral SDL tires a V in the tread design and will only rotate in one direction with the V pointing to the front of the car. The tires have some red dots on the sidewall only on one side. I wonder what that means.

[denisond3]

If the maximum pressure listed on the sidewall is 57 psi, it means the tire was designed to handle that much pressure, while supporting 1450 lbs each while underway - so it should be safe, assuming the tire was not defective. (I dont associate such high sidewall 'max pressures' with -inexpensive- tires). Carrying less weight per tire means that somewhat less air pressure is appropriate; but the weight/pressure relationship is NOT linear. Half as much weight on a tire does NOT go with half as much air pressure.
The tire pressure listed on the sticker on your door is the pressure recommended by the manufacturer, for the tires that were on it when it was made; which are usually listed on the sticker too. That lower pressure will give you a softer ride, but still be safe for any sane driving. Maybe it was chosen by the legal staff to minimize product liability lawsuits?
On my Escort I would use a tire pressure a little higher than 32, perhaps something like 40 to 44 psi. A higher pressure will help with miles per gallon (but not tremendously). The pressure for maximum tread-life seems to be higher than the pressures listed on the sticker on the door - but I have no clue how much higher. The manufacturers cant help either, since "best tread-life" would vary depending on how much weight the tire was supporting & the rim mounting width. With higher pressures I think it is more important to rotate the tires periodically, due to pattern-wear happening on the rear tires.
With 4 non-skinny adults riding in an Escort, I would guess the front tires carry about 900 lbs each, the rear tires about 800 lbs each.
Here is a url about Dunlop tires. They mention the 'dots' on the sidewall at the bottom of the page: www.dunloptires.com/care/tech.html.

[Davescort97]

Originally Posted by denisond3

If the maximum pressure listed on the sidewall is 57 psi, it means the tire was designed to handle that much pressure, while supporting 1450 lbs each while underway - so it should be safe, assuming the tire was not defective. (I dont associate such high sidewall 'max pressures' with -inexpensive- tires). Carrying less weight per tire means that somewhat less air pressure is appropriate; but the weight/pressure relationship is NOT linear. Half as much weight on a tire does NOT go with half as much air pressure.
The tire pressure listed on the sticker on your door is the pressure recommended by the manufacturer, for the tires that were on it when it was made; which are usually listed on the sticker too. That lower pressure will give you a softer ride, but still be safe for any sane driving. Maybe it was chosen by the legal staff to minimize product liability lawsuits?
On my Escort I would use a tire pressure a little higher than 32, perhaps something like 40 to 44 psi. A higher pressure will help with miles per gallon (but not tremendously). The pressure for maximum tread-life seems to be higher than the pressures listed on the sticker on the door - but I have no clue how much higher. The manufacturers cant help either, since "best tread-life" would vary depending on how much weight the tire was supporting & the rim mounting width. With higher pressures I think it is more important to rotate the tires periodically, due to pattern-wear happening on the rear tires.
With 4 non-skinny adults riding in an Escort, I would guess the front tires carry about 900 lbs each, the rear tires about 800 lbs each.
Here is a url about Dunlop tires. They mention the 'dots' on the sidewall at the bottom of the page: www.dunloptires.com/care/tech.html.

Thanks for your reply. I read the dots mean the high side of the tire to be matched with the low side of the rim. I wonder how do you know where the low side of the rim is?

[denisond3]

I dont know about finding the low side either, unless its one of my steel rims that has signs of a hard knock from a pothole.

[Airjer_]

Funny, If you would have read a little further on the dunlop website you would have found this

"Proper Inflation SAFETY WARNING:
Serious injury may result from tire underinflation/overloading. Follow Owner's Manual and tire placard in vehicle."


and


"Always maintain inflation pressure at the level recommended by the vehicle manufacturer as shown on the vehicle placard or in the Owner's Manual. Higher inflation pressure increases stiffness which may deteriorate ride and generate unwanted vibration."


Not to mention offer less traction and consequently increases you braking distance!




Typically the "orange" dots are lined up with the valve stem. I've never heard a legitimate argument for or against doing it that way?

[denisond3]

I Did read the entire Dunlop website, and have read many D.O.T. and other websites about tires over the years; as well as product spec sheets put out by tire manufacturers before there was an internet.

I dont recommend anyone do what they arent comfortable with.
(I dont recommend anyone drive over the speed limits either). I have confidence in my years of experience though, for dealing with my own cars.
When driving my vehicles, I Always check the tire temperatures each time we stop in a rest area, for gas, for meals, etc. - either by touching them with my hand or with an infra-red thermometer.
I recommend everyone do this. If one tire is warmer than the others - you need to learn why! (The tires on the sunny side will be slightly warmer than the ones in the shade). I check the air pressure in my tires more often than most folks - along with checking the brake fluid.

[Davescort97]

Thanks much for the information. It was put to good use in determining what tire pressure I will carry. That's a good idea to monitor the temp of the tires. If one was low on air or if the brake was dragging it would increase the temp of the tire. OK the placard says 30 psi. That's too low for me. I am going to carry 35 psi. I'm not worrying too much about stopping distances beause I drive like an old man. Not that I am an old man. I acquired this habit when fuel was $3.55 a gallon here in Arkansas. Wasn't it odd that the price of gas went down just before the election.

[John81]

Originally Posted by Airjer_

Funny, If you would have read a little further on the dunlop website you would have found this

"Proper Inflation SAFETY WARNING:
Serious injury may result from tire underinflation/overloading. Follow Owner's Manual and tire placard in vehicle."


and


"Always maintain inflation pressure at the level recommended by the vehicle manufacturer as shown on the vehicle placard or in the Owner's Manual. Higher inflation pressure increases stiffness which may deteriorate ride and generate unwanted vibration."


Not to mention offer less traction and consequently increases you braking distance!




Typically the "orange" dots are lined up with the valve stem. I've never heard a legitimate argument for or against doing it that way?

Just right!

[MikeLantz]

As an engineer I think it is criminal that the tire stores are so stupid to not understand the difference between pmetrics and old 32psi tires. At one time, all passinger tires were 32psi. Now 35 and 44 are common. Older door stickers are for the old non-pmetric 32psi tire. Putting 30psi in a 44psi tire severly underinflates it and was not what the car maker intended. Always use a ratio. If the older door sticker does not specify p-metrics, take the number and divide it by 32. 30/32 is 94%. If your tire is a 44psi unit, use 94% of 44 or 41psi. Never go below 80% of the tire max rating. I see too many tres reuined by tire stores that insist they must go by the door sticker and don't apply common sense.