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How to PROPERLY select and size TIRES for PERFORMANCE

by Billy Johnson

The most important part of your car is not the engine, suspension, or brakes. It’s the TIRES!!!  This is because your car can only perform as well as the capability of its tires. I’m often asked which tire is best and what size to buy.  In this article I discuss my methods for choosing and properly sizing the right tires.  I’m not into the “hella-flush” or “stance” scenes so this article is focused towards those who care about the PERFORMANCE of their car, whether on the street or on the track.

Pirelli had the best slogan for a tire company: “Power is nothing without control.” This is true for all forms of driving since it does not matter how much power you have if you can’t put it to the ground, it doesn’t matter how much you spend on a big brake kit if they easily lock up the tires, and your $7,000 coilovers can only deliver the performance that your tires are capable of.  It really does not matter how great and expensive your car is or how much money you’ve put into modifying it if you cheap out on tires; which is the only component on your car that actually touches the road.

 

Bad Tire SizeI often see really nice cars with a ton of money thrown at it in power upgrades and ‘blingy’ wheels wearing an improperly sized tire or something that is obviously not up to the capabilities of the car.  Most people really do not understand the importance of their tires, not only from a performance standpoint but from a safety standpoint as well.  This includes the age of the tire.
GTLM series TiresIn order to have a better ‘show’, keep costs down, and regulate competition, most racing series use a “spec” tire.  For those series that allow for more than one tire manufacturer, tire wars ensue and millions of dollars are spent in developing tires which often determine the success of a team or car.

Tires are consumable and expensive, but this should not be a justification for crippling the handling of your sports car, sports sedan, or minivan.  Whether you’re trying to break records and win races on the track or simply avoiding an accident on the street, choosing the right tire will often dictate the success of either.

There are 3 main steps that I follow when looking for tires: CHOOSE A TIRE CATEGORY, SIZE THE TIRE, and SELECT A TIRE.  SIZE & SELECT A WHEEL is my fourth and last step when also looking for new wheels.

 

STEP 1:  CHOOSE A TIRE CATEGORY

 

“What is the car being used for?”

Buying the right tires for your grocery-getting, baby-hauling daily driver in the northeast or Florida (where it rains most days of the week) is going to be a lot different than buying tires for your weekend toy in Southern California that never sees rain.  Determining the importance of dry, wet, snow performance, tire longevity, ride quality, and comfort should be the first step when looking for a tire. 

Just like everything in life, choosing the best tire is often a compromise since it’s rare to find a tire that is really good in the rain, quiet and lasts a long time that can perform well in the dry and hold up to extensive track use.  Usually as you increase the dry capability of a tire, you start to suffer wet performance and comfort in terms of noise and ride quality.  However, in recent years a few manufacturers are starting to make tires that are very good in all categories.

TireRack.com is a great source of information for everything tire related.  They have numerous customer reviews, independent tests, and are a pleasure to do business with.  They break down tires into 5 main categories, while I added a 6th.  These 5 main categories are further broken down into sub-sections like “Ultra High Performance”, “High Performance”, “Performance”, “Touring”, etc…  I won’t go into detail since I usually pick tires from the top sub-section of every category.  I have arbitrarily listed some examples for each category below:

 

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Comments
Crousti
Croustilink
Wednesday, September 09, 2015 4:53 AM
Have you tried federal 595 RSR ? Not the SS, the RSR.

Think of them as a little worse than a R888 on the dry (not by that much), and better when it rains. They resist wear and temp better than R888 too... and cost half.

Quite nice for budget track day, not good enough if you need better times and can get a set of R888, but really worth it if you want grippy tyres for fun.

8695Beaters
8695Beaterslink
Wednesday, September 09, 2015 5:40 AM
Awesome article Billy, thanks for all the tips! There is way too much bad or misguided info out there and it's great to hear from a pro driver on this topic.
Stigmsr
Stigmsrlink
Wednesday, September 09, 2015 6:33 AM
Great article. I will definitely share this with a lot of people.
Connor Harrison
Connor Harrisonlink
Wednesday, September 09, 2015 7:04 AM
Great info here! I know I learned a thing or two about tires. Thanks Billy!
Finch204
Finch204link
Wednesday, September 09, 2015 1:19 PM
Good eye-opening article on selecting tires and wheels. Thanks for sharing.
SlowJim
SlowJimlink
Wednesday, September 09, 2015 1:41 PM
My 18x10 wheels measure approx. 11" in width. So do I need to look for tires that have a 10" tread width or 11"?
bigBcraig
bigBcraiglink
Wednesday, September 09, 2015 1:47 PM
I've gotta point out that the "Tire Volume" listed here, while useful, could more accurately be labeled "Tread Area". Width*Circumference*carcass thickness would give a true volume but thickness isnt often published.

@SlowJim - wheel width is defined as the distance between the inside surfaces of the beads on the wheel, not outside of flange to outside of flange. If it's called an 18x10, this article says look for 9.5-10" tread width
Garret
Garretlink
Wednesday, September 09, 2015 5:54 PM
Yo Billy,

how is this actually possible

There are a few things to understand in regards to tire width. A WIDER TIRE:



Does NOT change the contact patch SIZE when the vehicle weight and tire pressure is the SAME.


So you're telling me a 9 inch wide tire will have the same size contact patch as a 10 inch wide tire? how does 9 inches of tire touching equal 10 inches of tire touching?
BillyJ
BillyJlink
Wednesday, September 09, 2015 6:35 PM
@bigBcraig - thank you for pointing that out, we changed it accordingly.

@Garret - Vehicle weight and tire pressure dictates the contact patch size. For simple numbers:

If you have a theoretical car with a 5" wide wheel that has the tire pressure and weight to have a 2" long contact patch (5" wide x 2" long) = 10sq. in contact patch.

Now if you put on a 10" tire with the same tire pressure and don't touch the car's weight, the contact patch will be 10" wide x 1" long = 10sq. in. The contact patch SIZE is the same, while the SHAPE is different.
Htpzt
Htpztlink
Thursday, September 10, 2015 1:18 AM
@billyj - It says in the article: "Increasing the Diameter also changes the contact patch SIZE". Shouldn't that also mean shape, when the size only depends on pressure and weight?
BillyJ
BillyJlink
Thursday, September 10, 2015 5:50 AM
@Htpzt - It should mean shape, not size. It's been fixed in the article. Thanks for catching that :)
warmmilk
warmmilklink
Thursday, September 10, 2015 10:05 AM
the summer category on page 2 a bit off. the Michelin's, Pirelli's, and Conti's listed in that category are a good bit off the performance capability of the rest of the tires in that list. especially the Pirelli's...
moranor
moranorlink
Wednesday, September 30, 2015 11:56 PM
thanks for this in depth writup it really goes a long way to build understanding on the subject :)

if i read correctly is it possible to get enough width in a 'max performance' street tire to replicate semi slick grip and heat capacity?

I am trying to make a fast street car so running the same tire on both the street and track would be very appealing if this is possible

most guys in my class are running 225/45/17 Semis if I could replicate this grip level with a wide street tire that can handle wet weather this would be a serious win
TnF
TnFlink
Sunday, October 18, 2015 1:20 AM
I own a Nissan 200SX (S13 aka 180SX/240SX but with a CA18DET) engine. The car is pretty moderate in mods, and since i'm always on a limited budget i'm still stuck to stock 280mm brakes, and aftermarket aluminium wheels that came with when i bought the car 7 years ago. The wheels are of a very rare size, R16 x 7.5J in 114.3x4!! I made the change recently to Yokohama NEOVA AD08R in 225/45R16 (special Japan/Europe only size) and i absolutely love them. Before i was running 225/50's and despite the compound change the new size is absolutely perfect for track use. I don't drift it, i like time attack, and the cornering potential has gone up the roof! (Certainly past what i feel comfortable to hold on with the stock seats!) In addition acceleration has been increased, center of gravity reduced even further, and rotating mass has also decreased. My only disappointment is that top speed (~250km/h) has been reduced (don't ask how i know) and longitudinal grip is not a big increase over the previous setup. This makes 1st gear totally obsolete as it is too short for the horsepower the engine is producing (about 300hp).

However with the suspension settings i'm running (-1.5o camber front, 10' toe out, ~7o non-adjustable caster up front, and -1o camber, 10' toe in rear) the car performs extremely fluidly, and so predictable while before it would shift suddenly from understeer to oversteer in a corner entered too fast. Suspension wise i'm running both front and rear strut bars, stock anti-roll bars, urethane bushings everywhere except rear subframe, rear driftworks lower and toe arms, bilstein b6 fixed dampers and tein springs. Ride height is stock, and i would say the springs are a bit too stiff taking into account the over 50mm travel i have available.

As for the drivetrain i use a cusco type-rs lsd configurable in both 1 and 2-way but i have it set up as 1-way since i don't drift. It is kinda weird for an FR vehicle but turn-in is not affected this way, and the pre-load makes it behave a bit like a 1.5way which would have been the ideal setup. The engine is running a GT2871R 52 trim 0.64A/R at 22psi and stock internals except intake cam (which has been replaced with another exhaust cam and dialed in using tomei gears), tomei metal head gasket and arp studs.

Feel free to let me know your opinion, i know it is a very unconventional setup for a S13, but hey don't most setups for this chassis revolve around drifting? :p
Brett Cherry
Brett Cherrylink
Tuesday, April 11, 2017 10:50 AM
@billyj can you get in touch with me. I have tried to find contact info for you but have not succeeded. I would like your help in choosing tire sizing for a project car I am working on. My email is: brettkcherry8@gmail.com Thank you.
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