Hi,

I am considering buying a set of 4 Volvo rims mounted on snow tires for $100 (slightly used). The size is P185/75/R14. The seller said that they came off of his 240. Two of the tires are Wintermaster Plus made by Wintermaster and two are Goodyear Ultragrip.

The tires on my 87 240 Wagon now are 185/70/R14 87T M+S (I do not know what 87T M+S means).

Here are my questions:

1) Why is the tire size on the tires for sale different than my tire size?

2) How good are Goodyear Ultragrip?

3) How good are Wintermaster Plus made by Wintermaster (my guess is that they are generic snow tires).

Note that I live in the Washington DC metro area and this will be my "snow car".

thanx
Kreg

While they pontificate about proper tire diameter, I would suggest two other factors to consider. Tire age and tread depth. Learn to locate and read the 4 digit DOT date code on tires (if it's 3 digits, the tire is from 1999 or older). It could be particularly useful when buying used snow tires because these tires may have been sitting around for 5yr ever since they sold their 240, and now the garage is being cleaned out.

And ask for tread depth measurements, or measure them yourself if/when you pick them up. Most people who quote tread by % remaining just don't know. Miles driven is also not a great indicator of treadwear. And the rest show depth on a coin. At 10/32nd, they'll probably churn through anything. At 5/32nd, still decent depth, but they will not be nearly as impressive.

185/75/14 is more than adequate for a 240 wagon. Search google for a picture of each tire to get an idea of the tread pattern. Some snow tires look like normal all seasons while others have small, chunky tread blocks with wide spacing. The latter will often be great in deep snow, but may give the squirelly ride and sloppy handling that snow tires are known for.
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forums.turbobricks.com

http://ejelta.com/tiresize/index.html?tiresize=245%2F75%2F16&minwidth=&maxwidth=&minratio=&maxratio=&minwheel=&maxwheel=&maxdelta=10


http://www.dakota-truck.net/TIRECALC/tirecalc.html

These should help you see the wicth and diameter of these Snows.

Not sure about the quality of these tires but I do not like running different tires on my vehicles. Snow tires make the car a bit loose at highway speeds as it is, combine it with two different types of snows...that would make me leary.


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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Tony,

Thanks!
I REALLY like the first calculator mentioned in your post.
I'm saving that address.
--
Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, open-front airbox, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, quad horns, tach, small clock. Wifemobile '89 245

I think that $25 each for four mounted tires on four factory wheels is pretty good for spares. I ain't never heard of "Winter Master", but I live in New Mexico.

I have never read reports on either, but to me this sounds like a good price. The wheel sizes are the same, the 70 to 75 only means that the distance from rim to the ground, the wall of the tire, is a different size. Not by much though.

These two tire sizes will have slightly different outer diameter (and circumference) from your true stock tire size (see below).
Neither is the stock original size spec'd for 240 wagons.
But there are plenty 240 wagons running around on those size tires.
P185/75/R14 (offered tires).
185/70/R14 (your tires - size was spec'd for 240 sedans)

Check your passenger door for a tire size label.
The ones I've checked on 240 wagons say 185/R-14.
Tire size calculator (below) shows that 195/75/14 is a very close match for the original 185/R-14.

At the $100 price, the 185/75-14's would make sense unless you regularly load your car close to max and/or like to drive it hard in curves or braking.

Please see this site for a good comparison tire size calculator.
http://www.wickedbodies.net/Tire-Size-Calculator.htm

If you enter "R" it will calculate, substituting 82 as the value for "R".
My own research showed that 80 may be more accurate. You can enter 185/80-14 as your stock size. You will see that your current size and also the 185/75's will
give you some speedometer error. If you check load ratings on tires from TireRack you'll see that tires with correct OEM diameter (like 195/75-15) will have a load rating of 92, if I recall correctly.

87 is a load rating, "T" is a speed rating.
M+S = "Mud and Snow"; I think it designates an "all season" tire but I'm not certain.
For a good education on these see tirerack.com and look in the Tech section.
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Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, open-front airbox, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, quad horns, tach, small clock. Wifemobile '89 245

"My own research showed that 80 may be more accurate"

Can you elaborate? According to Michelin, the aspect ratio of the 185R14 tire is 82. There is a different tire size of 185/80R14, why would there need to be a separate 185R14 tire size if it has the same aspect ratio? Have you physically measured the height of the sidewall?

Zack
1980 245DL M46 287k
1988 745T+ M46 226k

My research -

My first step was to use the tire size calculator at
http://www.wickedbodies.net/Tire-Size-Calculator.htm, since it will let you enter "R" as the aspect ratio when comparing two different size tires.

I compared two tire sizes, 185/R-14 and 185/x-14, plugging different values into "x" till I found the one that matched the circumference dimension the calculator gave me for the "R" tire. 82 was a perfect match, so I know that calculator converts "R" to an aspect ratio of 82 before running its comparison calculations.

Basic size information - tire sizes:
First # in tire size is the section width
Second # is aspect ratio
Third # is the rim diameter

Next I used the tire dimensions provided on the "specs" pages at tirerack.com.
I searched for tires in size 185/R-14 and found several - maybe six?? Not that many but enough to do calculations with.

Now by using the tire size formula in reverse I was able to derive the tires' sizes in conventional terms, from their actual dimensions on the specifications pages. Those tires calculated out to being size 185/80-14. (see notes on the calc process further down)

I do wonder whether possibly those factories are set up only to build tires in current standard dimensions. An 82 aspect ratio is between 80 and 85 so maybe they're making the tires 80 out of convenience when back in the 1980's they actually were built as 82? I have no way of knowing.

Another check would be to test the same reverse-calc process on some conventionally sized tires like 195/75-14. Get their dimensions, calculate the tire size from that, and verify the aspect ratio is 75 (in the case of that particular tire size).

I won't quote the formula (it's been a while) but the guts of it are:

Tire overall radius is
Rim radius (for a 14" rim, half that is 7")
Plus the sidewall height.
Times two for the overall diameter.

Section width is NOT the tread width. Section width is the maximum dimension across the inflated tire sidewall, front side to back side.

Sidewall Height and Aspect Ratio:
Section width x aspect ratio = sidewall height
So if section width is 185 (mm) and aspect ratio is 70 then
185 x .70 = 129.5 mm. sidewall height.

You can add the rim radius to the sidewall height to get the overall tire radius, then multiply x 2 to get the overall tire diameter.

Since the rim is 14", the radius is 7".
7" x 25.4 mm/inch = 177.8 mm rim radius
Add the sidewall height of 129.5 mm + radius of 177.8 = 307.3 mm overall radius
307.3 mm. overall radius x 2 = 614.6 mm overall diameter
614.6 mm. / 25.4 = 24.197" overall diameter
for the 185/70/14 tire.

I just looked up a Yokohama tire, 185/70-14 on TireRack, and it's spec'd at 24.3" overall diameter. Off by .1 inch from the calcs above. Several others also were spec'd at 24.3". Drive it 10K miles and it will probably be a perfect match. Dunno if that's the reason for the difference, or if there's another reason.

Anyway, the difference between 185/R-14 (orig. size) and 185/75-14 (offered snow tires) is at least .72" diameter, so the .1" discrepancy I found above is insignificant in comparison. .1" is far less than the tire will change in its lifetime due to treadwear.

--
Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, open-front airbox, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, quad horns, tach, small clock. Wifemobile '89 245

Assuming the same tire model and the same max sidewall pressure, load capacity will be the same when overall diameter is the same, and will increase when diameter increases. In fact, checking ratings across different tire brands and models, the only variables that significantly affect load capacity are those two: overall diameter and max sidewall pressure.

Which is why I'm always after getting a tire with the right overall diameter. Load capacity and speedo/odometer accuracy. Sidewall pressure will be one of two or three commonly used ratings but "casual" size selection will be inaccurate.

Which means that if you match the OEM diameter your speedometer will not lie and your load capacity will be as the engineers intended.
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Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, open-front airbox, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, quad horns, tach, small clock. Wifemobile '89 245