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870 Posts
Discussion Starter #1
Do to the large amount of reposted material I see entering this section of the forum I chose to write this guide to hopefully help clear up some questions. Below youll hopefully find answers to your wheel or tire need.

Warning: This is not a comparison test about tires for our cars. If looking for that look around and ask others what they've had success with.

Vocabulary: This may seem stupid I know, but youd be surprised.
(The capital letters below are not suppose to portray anger or shouting I just want to make sure people see this.)



A: How to read a sidewall

For instance when looking at your tires on your P-type wheels
you may have noticed Set of numbers that go like this below.

P225/60R14 94S ( example used was a BF Goodrich Radial TA)

Lets break it down.

The "P" Stands for the tires application which is passenger car. If your looking at your Tacoma instead of a P it says "LT" which is Light Truck.

"225" = your section width. Wich is the linear distance between the outside sidewalls of an inflated tire without any load.

"60" = your aspect ratio. Which is the sidewall hieght of your tire.
This 60 means if you took 60% of your section width which is 225mm
youd end up with how high your sidewall is.

"R" = Radial. Meaning the tire on your rim is a Radial construction type tire.
Most tire's today are Radials due to the better performance, quieter ride, and longer tire life. Others include "B" for Belted Bias and "D" for Diagonal Bias construction.

"14" = Rim size/diameter. Meaning you have a fourteen inch wheel.

"94" = Your load index. Or how much wieght the tire can support at its maximum inflation pressure. The higher this number the more wieght the tire was designed to carry. A "94" series tire is built to take loads not in excess of 1,477 LBS.

"S" = Your speed rating. These ratings range form Q to Z, with Z being the Best. The "S" indicates that the tire was designed for speeds up to 112 MPH.

NOTE: Your speed rating is not a suggested speed limit nor a licsense to travel at high speeds. Traveling at these speeds on public highways is stupid period.

B: A breakdown of the speed ratings in Miles Per Hour (MPH).

Q=100, R=106, S=112, T=118, U=124, H=130, V=139,

V=149, W=168, Y=186, Z=149 and over.

C: A breakdown of the load index in pounds (LBS).

0=99, 1=102, 2=105, 3=107, 4=110, 5=113, 6=116, 7=119, 8=123,

9=128, 10=132, 11=136, 12=139, 13=143, 14=148, 15=152, 16=157,

17=161, 18=165, 19=171, 20=176, 21=182, 22=187, 23=193,

24=198, 25=204, 26=209, 27=215, 28=220, 29=227, 30=234, 31=240,

32=247, 33=254, 34=260, 35=267, 36=276, 37=282, 38=291, 39=300,

40=309, 41=320, 42=331, 43=342, 44=353, 45=364, 46=375, 47=386,

48=397, 49=408, 50=419, 51=430, 52=441, 53=454, 54=467, 55=481,

56=496, 57=507, 58=520, 59=536, 60=551, 61=567, 62=584, 63=600,

64=617, 65=639, 66=661, 67=677, 68=694, 69=716, 70=739, 71=761,

72=783, 73=805, 74=827, 75=852, 76=882, 77=908, 78=937, 79=963,

80=992, 81=1019, 82=1047, 83=1074, 84=1102, 85=1135, 86=1168,

87=1201, 88=1235, 89=1279, 90=1323, 91=1356, 92=1389, 93=1433,

94=1477, 95=1521, 96=1565, 97=1609, 98=1653, 99=1709, 100=1764,

101=1819, 102=1874, 103=1929, 104=1984, 105=2039, 106=2094,

107=2149, 108=2205, 109=2271, 110=2337, 111=2403, 112=2469,

113=2535, 114=2601, 115=2679, 116=2756, 117=2833, 118=2910, 119=2998,

120=3086, 121=3197, 122=3307, 123=3417, 124=3527, 125=3638, 126=3748,

127=3858, 128=3968, 129=4079, 130=4189, 131=4289, 132=4409, 133=4541,

due to space constraints I could not compleate the load index. it goes to 150

D: How to read traction, treadwear, and temperature of a tire
or your (UTQGS). This stands for Uniform Tire Quality Grading System.
The traction and temperature letters and treadwear number is found on the side wall of your tire. If you cant find these, say on a BF Goodrich
Radial T/A that has Black lettering out its on the reverse side or the white lettered side.


NOTE: It is important to note that that the traction test that determines

the letter your tire or the tire your looking to buy recives is based on its

ability to stop or break, in a straight line on wet asphault or concreate, and

not a direct representation of the tires avalible grip while cornering or turning.

The traction scale breaks down as follows.

AA=Excellent, A=Good, B=Fair, C=Poor or Adaquete (i hope i spelled that right)

2. Treadwear

Note: As it is impossible for the US government to test each induvidual tire

for treadwear due to time and cost restraints these numbers tend to vary slighty form manufacturer to manufacturer. But are a reliable way to

determine how long the tire should last if kept properly inflated, rotated every 6-8,000 miles, and not abused by heavy braking, heavy acceleration,

dirfting, autocross, racing, burnouts, and any other automotive pleasures that I may have missed, that we all enjoy. Also make sure to keep your

viechle's alignment in check as this can quickly wear out the shoulders of the tire. Its also important to make an honest self evaluation of your driving

style, some people drive harder than others and wear there tires more quickly.

Instead of breaking down hundreds of numbers I'am going to give you this
general rule to determine the life of such and such a tire. Whatever your

treadwear number is add two Zero's behind it. if its 600 then 60,000 miles, if its 400 then 40,000 miles, if its 150 then 15,000 miles and so on and so

fourth. Remember these numbers only mean anything if you dont stray from the rules above.

3. Temperature

These letters determine how hot the tire runs. The scale runs from A, B, and C.
A being the best and C being the worst. So A=Coolest running tire by

U.T.Q.G.S. standards and C=Hottest or maximum temperature allowed.

E. How to read your DOT number. (DOT refers to Department Of Transportation.)

1. Your DOT number is a twelve digit number that includes letters, please do not be alarmed by this. This is also found on the sidewall of your tire fairly

easy because before this straign of numbers and letters it says DOT. If you only see eight numbers and letters that is ok because the whole DOT number

is only written on one side of the tire/sidewall. Being as the first eight numbers refer to where the tire was built and who was on the assembly line

that day we will disregard the first eight numbers for they really do not mean anything to you unless you work in the tire industry. But the last four

numbers are of concern and yes no matter what tire you have the last four markings on your DOT will always be numbers. These numbers tell you in

what week and year your tire was manufactured. Thus for if your last four digits read 1204 your tire was built in the 12th week of the year 2004, and if

your tire reads 0105 your tire was manufactured in the first week of the year 2005, if your tire reads 0606 that means it was manufactured in the sixth

week of the year 2006. And if your still struggling to understand this, of the last four numbers of your DOT, the first two digits refer to the week (01-52)

your tire was manufactured in and the last two digits refer to the year your tire was manufactured in. 1999=99, 2000=00, 2001=01, 2002=02.

If the last two digits show that the tire is older than eight years in age it should be replace regardless of tread amount left on the tire. The reason

being after a tire is eight years old the structureal integrity of the tire begins to breakdown and the possibilities of a blowout are greatly increased.

Trust me blowouts are not fun and usually happen when on the highway at speed, and more often than not in this scenerio your rim is sadly

destroyed with your tire as it meets the asphault at speeds usually starting at 45 mph and upwards.

F. Tire construction

Intro: Because virtually all tires today are Radial designed tires this is the only tire Iam going to breakdown and go into detail describing.

1. The nitty gritty of Radial tires.

What makes Radials so cool and effiecient compared to the tires of yesteryears, is in the design of the tires casing or in laymans terms bascially

your tires foundation, that is everything below the rubber surface of the tire. The Casing is made up of a series of cords usually polyester which make

layers or plies in tire speak. Radial tires have there plies posistioned so there cords run by each other in circular bands across the tread of the tire. This

lets the Radial tire flex and soak up bumps and uneven road textures while producing less friction therefore longering tire life. At the top of the Radial

Casing there are usually steel belts which are either woven strands or steel cords. This is preatty much the skeleton of the Radial tire protecting it

from bumbs and punctures. This skelaton also stiffens the tire producing more consistant handeling and longer treadlife. Other things you may find

in modern radial tires are cap plies and bead chaffers but these are most typically found in sport tires for the purpose of improving stability and

conering at high rates of speed. The tread of a modern Radial consists of three basic elements. Grooves for channeling out water, the tread block

itself which provides traction, and within the tread block sipes or little cuts in the block which help increase the traction of the tire.

870 Posts
Discussion Starter #2
Section 2 Wheels Section2 Wheels Section 2 Wheels Section 2 Wheels

Note: As in the tire section, in this section I will not be doing any direct comparison between which brand of wheel is better than another. Iam simply

trying to educate and answer questions so you will hopefully by reading this know what you need for your desires and will understand what youre looking at.

A. General Stuff pertaining to our cars.
Our bolt pattern: Which is 4 by 4.50 or 4 by 114.3 they both mean the same thing any tire or wheel guy if you say either one will know what your talking about.
Our offset for our wheels: Which is Zero. Some people call this the rear wheel drive offset but I hate that term I perfer Zero offset.

B. All these differant types of wheels which do i choose.

Intro. As new forging techniques arise and al the multi piece wheels out there its easy to get confused on what you really need especially if you dont

know differances like gravity casting and forged or semi solid forged. Below is a list of the methods the industry is currently using and there pros and

cons. This pertains to aluminium wheels only bescause currently Volk is the only wheel manufacturer to offer magnesium wheels which means you

probably dont have a set on your car and iam no expert when it comes to magnesiun so I wont pretend to be.

1.GRAVITY CASTING: The most common method used

Gravity Casting works like it says. Its a very basic method of pouring molten aluminium in a mold and letting god and the laws of Sir Isaac Newton do the

rest. This is a good method for wheels that are meant to be pleasing to the eye and not really meant to be as light wieght as possible. Scince gravity

is used to fill the mold the aluminium is not as densely packed which equals air pockets, which can greater the increase of pitting or strees cracks. Its

also important to note that gravity cast wheels will have a higher wieght to achieve the desired strength.

Low pressure casting uses pressure to move the molten aluminium into the mold at a quicker rate. Thus making a wheel that is denser/stronger

and lighter than a gravity cast wheel.

High pressure casting utilizes the same techniques as low pressure casting but with higher pressure creating an even lighter and stronger wheel than the
low cast unit.


Tilt die casting is a new method for casting wheels. In tilt die the mold is tilted to almost 90 degrees before the molten aluminium is poured and then

the mold is moved back to its resting position. The reason for this process is to reduce the bubbling effect of the aluminium which inturn reduces air pockets.

Due to the high costs in running this mold process expect to pay a premium on tilt die cast wheels.


Forging is taking a solid peice of billit aluminium and forcing it between two forging dies at pressures from 8,000 to 10,000 tons thus creating the shape

of a wheel. After being forged the wheel is machined down to get the exact detail the manufacurer is after. Forging creates a very dense and strong wheel that can be very light.


Semi solid forging is a process of heating a billit of a special alloy to an almost liquid state then forcing it into a mold at a very high rate. In the end

you get a wheel similar in stregth and weight of a forged unit but at less of a cost to you because of the high tooling and production costs of forged

wheels. To date only SSR (speed star racing) is licensed to use this process.


Note: Due to the vast number of wheels available I will not be naming the correct spacer you need to fit such and such a wheel to your car.

The purpose of this is so you can learn to identify the differant offsets and then choose the wheels that best suit yours or your friends cars.

1.POSITIVE OFFSET (most common)

A positive offset is when the hub mounting surface is on the side of the wheel you see or street side. To determine this find the center of the wheel

this is your center line if the mounting surface is not centered on the line or pushed behind the center line it is a positive offset wheel.


Zero offset is when the hub mounting surface is centered within the rim on the center line. To determine this check to make sure the mounting surface

is not pushed back behind the centerline or portruding in front of it.


Despite the name this is not bad its just how some cars roll. In excess though negative offset will cause steering wheel kick back and stress

suspension components. Negative offset is when the hub mounting surface is pushed behind the cener line of the wheel.

1. Bolt hole: Where your lug nut or lug stud goes into.
2. Valve hole: The hole your valve stem sticks out of.
3. Bolt circle: The imaginary circle that makes up all of your bolt holes
4. Center bore: The hole in the very center of your wheel.
5. Wheel face: Used to describe the front design of your wheel.
6. Outer Rim: The outside part of your wheel excluding your wheel face.
7. Inner Rim: Opposite above.


Below is a simple mathmatical equation if you have a caculator to determine the hieght of your wheel and tire package. Once the hieght of the factory

setup has been figured you can go to larger rims and lower profile tires to see if they meet the same hieght. The equation goes as follows.


so if you have a stock MK2 P-Type wheel and tire(225/60 14) setup the equation works like this.

(225X0.60)X2 =270

SO 270/25.4=10.62

SO 10.62+14.00=24.62"

Well thats all I can squeeze into tonight guys hope this information helps if not i just wasted a couple hours of my life

1,305 Posts
Awesome write-up! Just took a quick skim through and I think there is an error in the offsets section...particularly the postive offset....shouldn't it be pushed "ahead" of the centerline? Just thought I'd point it out since you have behind written down for positive and negative. ;)

Great job in the meantime!!


4,517 Posts
Very nice. Edit the B section in the first post and tell us what the V speed rating really is: 139 or 149 mph? You have it listed twice with a little conflicting info. Enquiring minds want to know!

Great sticky!

3,270 Posts
Just a niggly thing, I wouldn't say the offset for our wheels is "zero". stock P-types are +8, and L-types are +22 or thereabouts. If anything you might want to say that low-offsets are preferred for P-types.

870 Posts
Discussion Starter #7
Sorry for the speed rating V=149 mph. Concerning the positive offset its a little confusing iam sorry. I meant that to determine positive offset find the

wheels center and this is your centerline. if your hub mounting surface is before centerline or on the street side of the wheel (pushed out) the side facing you its a positive offset wheel.

For some reason I cant edit the above post so if a moderater could help me out with gettng this info above that would be great.

Slip sorry i thought that it was implied but I read it agian and its not really but yes P-types do like low offsets in the Zero to 10 degree range thats

why I called it a Zero offset. And I dont remember ever refering to L-types but thats good info about there offset.

9,445 Posts
Good wheel info!!! I will add in my 2 cents here, so that I no longer have to keep repeating myself all the time.

Stock wheel offsets:

14 x 7" P-Type wheel: +8mm

14 x 5.5" L-Type wheel (82 - 84): +27mm

15 x 6" L-Type wheel (85): +20mm

14 x 5.5" 79 - 81 MKI aluminum wheel: +27mm

14 x 6" P-Type wheel (the "Van" wheels like on Terrasupra's L-Type): +21mm

40 Posts
now my 2 cents
verry nice break down !! but can i put 24's on a supra ? or do you think thay will fall off the roof ??? :zzzzz:

3,270 Posts
you can put p-type wheels on an l-type, but the fronts will stick out further than you probably like.

p-type size tires (225/60/14) on an L-type rim will physically fit, but is a very bad idea. L-type wheels are not wide enough.

the above info assumes you do not have 85 L-type 15" wheels.
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