Thread: "THE" Definitive Tire Thread

Discussion Thread found here:
http://www.sr20-forum.com/suspension/29503-discussion-thread-re-definitive-tire-thread.html


Okay, there's lots of good information floating around here for daily/track/drag/etc. tire use. Problem is, that they're POSTS within other's threads. This makes it rather difficult to find the information quickly.

Thus, I give you "THE" Definitive Tire Thread!

Deciphering the Code: "XXX/YY/ZZZZ"

XXX refers to the tread section width, from sidewall to sidewall. This is measured in MM. (205mm or 195mm, for instance).

YY is the aspect ratio. The aspect ratio will be used to help you calculate the actual sidewall height from the edge of the wheel, to the tread section of the tire.

ZZZZ is NORMALLY listed as something like 13-28", but I posted it as ZZZZ since some tires are listed as ZR16's, or XR16's, etc. The last two characters are of the wheel size. You cannot use a 16.5" tire on a 16" wheel. The First character is the speed rating. This was commonly used prior to 1991. It may or may not be used today by some manufacturers of tires. Typically listed as "V", "X", "Y", or "Z". The second character stands for "Radial", meaning radial belts. These tires are generally directional, and while they can be mounted on any wheel, they CANNOT be swapped to a side of vehicle that would have them "rotate" in the wrong direction at decent speeds. This can cause radial belt separation, and result in a fireball of death.

Going a bit further, lets look into the treadwear rating, the traction rating, and the temperature rating...

Treadwear Rating:

...The wear on tires that are being tested ("candidate tires") is compared to the wear of Course Monitoring Tires (CMT), which are sold by the NHTSA at its UTQG test facility in San Angelo, Texas. Both types of tires are mounted on vehicles that will be driven in a convoy during the test, thus ensuring that the candidate tires and the CMT tires experience the same road conditions. The convoy, typically one of four or fewer vehicles, will drive 7200 miles on public roads in West Texas. Candidate tire wear will be checked during and after the test, and compared to the wear on the CMT tires from the same convoy....

Oh look, there's that UTQG acronym again! This acronym stands for "Uniform Tire Quality Grade", and is a standard developed by the NHTSA (National Highway Traffic Safety Administration).

The Treadwear Grade describes how a tire manufacturer views the wear of a given tire. In theory, this means that a tire with a 200 grade will wear twice as long as a tire with a 100 grade. However, tire manufacturers are not under any obligation to grade a tire based on the test results, except to say that they can not overstate the grade. This is enforced by NHTSA requiring documentation to justify any assignment of a grade on a tire.

Please note: As Course Monitoring Tires have changed, their treadwear grades have changed to numbers considerably higher than 100. As a result, it would be incorrect to say that a tire with a treadwear grade of 200 gets twice the life of the Course Monitoring Tire.

Keep the BOLD RED statements in mind, kiddies. There are many other factors including environment and driving characteristics that change the overall outcome of the treadwear. Consider it a Ratio, and not an actual treadwear "expected lifespan". This is where the term "Your Mileage May Vary", or "YMMV" is coined

Treadwear ratings are issued by the tire manufacturer, and NOT the NHTSA. As long as the treadwear rating is equal to or lower than the "control" tire, then the NHTSA does NOT get involved. Therefore you could EASILY have a tire that outlasts the expected ratio of say "440", since the manufacturer can UNDERRATE their tires, but cannot OVERRATE without written justification to the NHTSA. (Think about this, NHTSA may end up using that tire as the control for future testing, which could hurt other manufacturers and their ratings )

Another fact I love to point out: Tires such as "DOT Racing" Tires, hold almost ZERO commercial value, and therefore can be given ratings as low as ZERO. Yep, that's right. The tires WE LOVE THE MOST, generally aren't even rated. Technically, there shouldn't be a rating anyway, since we don't expect tires that are specifically TRACK USE to be used on the street and outlast our Nissan Armada's factory Michelin Tires.

NOTE: Please review the below link as it pertains to SCCA Solo Rules for treadwear categories.
http://cms.scca.com/documents/Solo_Rules/solo_categories.pdf

Temperature Grades:

Temperature grades represent a tire's resistance to heat and its ability to dissipate heat when tested under controlled laboratory test conditions. The grades from highest to lowest are "A","B" and "C". The grade "C" corresponds to the minimum performance required by federal safety standard. Therefore, the "A" tire is the coolest running, and even though the "C" tire runs hotter it does not mean it is unsafe. The temperature grade is established for a tire that is properly inflated and not overloaded.

Another pretty obious explanation of Temperature Grades. I can't think of any tires that have a temperature rating lower than "A" on most street/track tires.

Traction Grades:

Traction grades represent the tire's ability to stop on wet pavement as measured under controlled conditions on asphalt and concrete test surfaces. As of 1997, the traction grades from highest to lowest are "AA","A","B" and "C". A tire graded "AA" may have relatively better traction performance than a tire graded lower, based on straight-ahead braking tests. The grades do not take into consideration the cornering or turning performance of a tire!

What does this mean to you? Traction Grades mean very little to the overall characteristics of a tire. You will likely only see "A" as the traction grade, anyway.

Time to look at a tire:

Take a stock B14 SE-R wheel. It's a 195/55/15. In order to calculate the sidewall height in inches, convert the 195mm to inches, (~7.67"), then multiply by .55, which is the aspect ratio. The result is 4.21" in sidewall height.

In order to calculate the overall diameter of the above tire, multiply the sidewall height you've just obtained (4.21") by two, and then add the diameter of the wheel. With this being said, we now know that the rolling diameter of the tire is 23.42".

This is especially beneficial to you, since you can now look for a tire that will give you a similar overall diameter close to what you currently have. This is ESPECIALLY beneficial when you want to keep your rolling diameter as close to stock as possible, so that your TACH and SPEEDO are relatively close to what the OEM has configured. OR, you can be like me and not care. It's all about how the tire performs, and not about being a few mph off on the highway. After all, damn near everyone I see has GPS in their car (as do I). I'd trust GPS WAY more than an instrument cluster from my econobox.

Keep in mind that some manufacturers may stray a bit from the stated tread width. The guide was to give you a decent approximation.

SECTION VIII (No, not Sec. 8 Housing Authority...)
For more general information about wheels and tires on various Chassis designs by Nissan, see Shawn B's thread here:
A Few Words about Wheels and Tires...

I highly recommend you read the entire thread posted above, for other chassis specific modifications.

For the sake of posterity, the below links precluding "THE" Tire List are from SE-R.net. Another very good resource while doing tire hunting. Please note that this thread is only as good as you make it! The more independent reviews you have on tires, the better the thread =]

What's an ET? I don't wanna phone home...:

The offset of a vehicle's wheel is the distance between the centerline of the wheel and the plane of the hub-mounting surface of the wheel. It can thus be either positive or negative, and is typically measured in millimeters. Offset has a significant effect on many elements of a vehicle's suspension, including suspension geometry, clearance between the tire and suspension elements, the scrub radius of the steering system, and visually, the width of the wheel faces relative to the car's bodywork.

Zero Offset - The plane of the hub mounting surface is even with the centerline of the wheel.

Positive Offset - The plane of the hub mounting surface is shifted from the centerline toward the front or outside of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

Negative Offset - The plane of the hub mounting surface is toward the back or brake side of the wheel's centerline.
"Deep dish" wheels typically have negative offset or a very low positive offset.

To maintain handling characteristics and avoid undue loads on bushings and ball joints, the car manufacturer's original offset should be maintained when choosing new wheels unless there are overriding clearance issues.
Wheels are usually stamped with their offset using the German prefix "ET", meaning "Einpresstiefe" or, literally, "insertion depth". An example would be "ET45" for a 45mm offset.

Okay, so how do I calculate it?!

It's actually pretty simple. First, measure the wheel's width from the outboard flange to the inboard flange. Then divide by two. This is your centerline. You'll probably know what the wheel's width is already, so just divide that number to achieve the same result.

Once you have the centerline, measure from the hub-mounting surface of the hub to the edge of the inboard flange (if the wheel were laying flat on the ground – face up – your measurement would be from the ground to the hub-mounting surface). This is your back spacing.

Back spacing - Centerline = Offset

Can I haz Piktar?!



More Reading on Tire Offset:

GREAT article on offsets. It's been floating around for a little more than a year, and was in Honda Tuning Mag, however the GENERAL idea applies no matter the make/model of vehicle.
Wheel Offset: Why it Matters - Guide To Proper Honda Wheel Offset - Honda Tuning Magazine

Miscellaneous Links, Tire Related:

Tire Wheel Sizes
Tire Impressions
Tire size calculator
Custom wheels, car rims, truck wheels - WWW.RIMSNTIRES.COM
Online Wheel & Tyre Fitment calculator. Offset and Tyre Stretch

"THE" Tire list:

Daily Duty/All Season:
Falken ZIEX ZE-512 #2
Kuhmo Ecsta AST
Bridgestone Potenza GIII

Performance Street/Auto-X/Hill Climb/Time Attack Tires:
Falken Azenis RT-615 #2 #3
Dunlop Direzza Z1 Star Spec #2
Hankook Ventus R-S2
Kuhmo XS
Yokohama S-Drive

Auto-X/Hill Climb/Time Attack Tires:
Yokohama Parada Spec II

Roadcourse Tires:
Toyo RA-1

DOT Street Legal Drag Racing Tires:
Mickey Thompson ET Street Radials

Drag Racing (NON DOT Legal) Tires:

Cold Weather Tires:

Poor Performance Tires: BUY AT OWN RISK!
Kuhmo Ecsta ASX
Kuhmo Ecsta Supra 712
Toyo Proxes 4's

Last season for autocross I ran a Dunlop Direzza Z1 Star Spec in a 205/45/16. The Star Spec is Dunlop's ultra high performance summer street tire. The tire features a UTQG rating of 200AA.



I drive pretty aggressively when I race and put a lot of abuse and load on the tires, rarely would these tires give up, and when they did it happened gradually, giving me plenty of warning to correct appropriately. The courses these tires were run on were either go kart tracks, paved circle tracks, or parking lots, as such the paved surfaces were pretty haggard/torn up. These tires were used for 7 autocross events and daily driven for approximately 6 months or 10K miles, they probably have another 2-3K miles left in them, and would have had more if my car was properly aligned :o. These tires also have excellent grip in damp or moist conditions, for a high performance summer tire.



I would classify these as a Road Course/AutoX tire, and wouldn't suggest them for daily usage if you'd like to get more than a summer's worth of usage out of them.

Currently there is a $50 mail in rebate from Dunlop, valid through April 17th.

Dunlop Tires | Current Promotions | Rev It Up

EDIT: I was planning on ordering a set of Falken Azenis RT-615s before the end of the month in a 205/50/15 to take advantage of their $80 mail in rebate, but apparently they are sold out for good. I guess I'll get some Kumho XS's instead...

Car: 1991 Sentra SE-R
Suspension: Hyperco Gen 2's with Koni inserts in B13 housings
Rims: Rota Circuit 8 with an offset of 38
Tire: Kumho Ecsta ASX -- High Performance All-Season
Size: 205/50W15
Important stats: Section Width on 6.5" rim: 8.4 inches
.......................Tread Width: Unknown
.......................Weight: 20lbs.
Use: Daily driving/spirited driving
Dates on car: 11/2005 - 3/2010
Miles on tire: Approx 50,000


Review: I initially bought these tires to barely get me through Michigan winters and still allow me to have fun in the summer. Two years in I inherited snow tires and after that they saw limited winter use. These tires suck. They replaced Falken Zeix 512's and they didn't come close. My to-the-wear-bars Falkens hydroplaned less than the brand new ASX's and the handling seemed less precise (possibly less stiff sidewalls?). The massive section width of these tires led to rubbing on the rear fender on hard bumps. These tires never inspired confidence and the levels of grip seemed really low. Breakaway was fairly progressive and easy to catch. Snow traction (it is all season) was enough to barely get places. Wet traction was low too. Very little road noise from the tires and fairly comfortable for just cruising around. As long as there were no puddles. I am going back to Zeix 512's now, which are 3lbs lighter per tire.

Car: 1991 Sentra SE-R
Suspension: Hyperco Gen 2's with Koni inserts in B13 housings
Rims: Rota Circuit 8 with an offset of 38
Tire: Falken Zeix 512 -- High Performance All-Season
Size: 195/50HR15
Important stats: Section Width on ?" rim: 7.7 inches
.......................Tread Width: 6.9"
.......................Weight: 16.8 lbs.
Use: All season daily driving/spirited driving and two road course sessions
Dates on car: 1/2004 - 11/2005
Life of tire: Approx 30,000 miles
Available at Discount Tire Direct for $62.00 ea.


Loved these tires. Just enough snow grip to get around and I never had trouble with hydroplaning. Grip, both wet and dry were great for all-seasons. I don't recall them being noisy, but I am buying them again soon so I will report back with more info. Handled two evening sessions on a road course with great manners. Not in the league of summer tires, but great all around, and cheap, tires.

Car: 1994 Sentra SE-R
Suspension: Road Magnet springs with KYB AGX struts
Wheels: 15x7 +38 Panasport UL

Brand: Kumho
Model: Ecsta Supra 712
Category: High Performance Summer
Size: 205/50/15
Weight: 16lbs.
Use: Daily driving/spirited driving/racing
Life: Approx. 15,000 miles (They should last a normal person 30,000 miles)
Cost: Approx. $60 per tire
Rim protector: Yes



Review: I got them because they were listed as a high performance summer tire so I thought they would perform well. They also have a very "cool" looking tread pattern and I believed it would handle the rain decently well. They are also very inexpensive.

The tires are quite bad for what they purport to be (high performance summer tires). They don't chunk or wear quickly when subjected to the heat of the track use (which is their only redeeming quality) but they never have any grip ever at any time and get greasy quickly with heat. They would be a decent dry/wet summer tire (they last a long time for summer tires) for the street if they were the only tire in existence. They have a cool tread pattern, and are inexpensive but other tires are better in every way for the same price. They have absolutely no performance capabilities. At the time of their initial release and especially now, there are all-season tires that cost less and out perform these tires. The fact that other all-season tires exist that are as good or better for the same price make these tires effectively useless.
Anyone I've ever spoken with who ran these tires echoed my experience. They thought they were decent until they tried another good tire (any other good tire).

Stay away.


(Great thread idea by the way Cliff!)

Car: 1994 Sentra SE-R
Suspension: Road Magnet springs with KYB AGX struts
Wheels: 15x7 +38 Panasport UL

Brand: Falken
Model: ZIEX ZE-512
Category: High Performance All-Season
Size: 205/50/15
Weight: Unknown
Use: Daily driving/spirited driving/racing
Life: Approx. 5,000 miles (They should last a normal person 40,000 miles)
Cost: Approx. $65 per tire
Rim protector: Yes



Review: I got these tires because I needed something cheap and decent, and I was sick of going through my previous tires (See Kumho Exsta Supra 712) so quickly. I thought an all-season tire would last longer.

The tires were great when driven normally and provided better grip than the Kumho summer-only tires! I raced on them however, and they quickly melted and chunked away.

Great all-season street tire. Horrible race tire (it can't take the heat).

(See Isfahan's review above as well.)

Car: 1994 Sentra SE-R
Suspension: Road Magnet springs with KYB AGX struts
Wheels: 15x7 +38 Panasport UL

Brand: Falken
Model: Azenis RT-615
Category: High Performance Summer
Size: 205/50/15
Weight: Unknown
Use: Daily driving/spirited driving/racing
Life: Approx. 10,000 miles (They should last a normal person 25,000 miles)
Cost: Approx. $95 per tire
Rim protector: Yes



Review: The famous Azenis RT-615 lived up to their reputation as a good auto-cross tire. Like any good auto-cross tire they don't need much or any heat in them to stick well making them good for spirited daily driving as well. They are a bit noisy especially as they wear down and their tread life is a bit less than normal but they are great tires if you want amazing lateral grip. Stay out of heavy rain (and obviously snow) and you'll be all set.

Highly recommended for street and/or atuo-cross.

Car: 1994 Sentra SE-R
Suspension: Road Magnet springs with KYB AGX struts
Wheels: 15x7 +38 Panasport UL

Brand: Hankook
Model: Ventus R-S2
Category: High Performance Summer
Size: 225/45/15
Weight: Unknown
Use: Daily driving/spirited driving/racing
Life: Unknown (I have not worn them out yet)
Cost: Approx. $100 per tire
Rim protector: Yes



Review: These Hankook tires were made to dethrone the famous Azenis RT-615 auto-cross tire. In many reviews they do just that. I can't compare them directly because the size I got was wider than the Falken RT-615s that I had. (These are one of the few tires available in the coveted 225/45/15 size.) Like any good auto-cross tire they don't need much or any heat in them to stick well making them good for spirited daily driving as well. They are not noisy like the RT-615s and are great tires if you want amazing lateral grip. Where the RT-615s don't handle rain very well these tires shine again. Stay away from snow though obviously.

Highly recommended even above the Falken Azenis RT-615 for street and/or auto-cross.

Car: 2003 Honda S2000
Size: 205-55/16 225-50/16 Stagger
Brand: Dunlop
Model: Direzza Sport Z1 Star Spec
Price: $105/116
Category: Street/Auto-x



I am really a fan of these tires for street use. I am an aggressive driver. Below 85MPH these tire are pretty quite for highway driving, unlike RT-615's. Very predictable behavior, very quite when they slip also. I'm not a "drifter" by any means, but I do put this car sideways every day. Very linear feedback. They don't really need a lot of heat either. I've used them for 5,000 miles so far, and from what it seems they have another 5,000 in them.

I haven't tracked these so I don't know how well they do with lots of heat.

I also run these on my Father's BPU 335i. Seems to hold the power nicely.

Try not to do over 80MPH in standing water, because they will hydroplane. But a very good wet tire too.

Car: 95 Trans-Am
Tire: Mickey Thompson ET Street Radial
Size: 275/60/15
Price:$182
Use: Street/Strip
Life of tire: Extremely Variant on use

A friend of mine let me drive his car with these on it. I was very pleased with their performance. With a light burn out, these were EXTREMLY sticky. If you are not careful, they will pull up asphalt. I would use these if you are into drag racing. Soft sidewall will equate to tons of torque steer on FWD cars. Not very good in water. These tires basically last a season.