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GarageLove How To: Tire Testing

by Per Schroeder

The neck-twisting grip that modern performance tires deliver was once the territory of just limited-production race compounds. Couple that delightful evolution with the rise of affordable data acquisition systems and more track-capable cars than ever before—and you just have to wonder—are we in the era where anyone can find the absolute best tire for their car? Can the hardcore enthusiast simply buy several sets of tires and figure out which brand works best for their car, track and driving style?

We won’t leave you hanging. The answer is a “Yes” with a few small, but important, “Buts” and that’s what we’re going to focus on. Anyone can figure out what tire works best in a certain application. It just takes time, money and the understanding that the narrower your focus is, the quicker and faster it is to figure all of that stuff out.

Professional automotive tire testing is broken down into two major categories: Objective and Subjective. Objective, in this case, refers to instrumented testing done in a tire manufacturer’s lab. This testing will highlight a tire’s coefficient of friction, wear and noise parameters in a tightly controlled environment. Subjective is what people typically imagine when they think of tire testing: A test engineer is set out on test road loops and closed tracks to feel, listen and evaluate the tire from behind the steering wheel.

 

Factory test drivers do this testing day in and day out, but it is possible to get good data by following some simple rules.  Rule #1 is to make things as consistent and repeatable as possible. 

The tire companies have a near unlimited budget for track time and tires, but if we work smart, enthusiasts and amateur racers can get it done on a more reasonable level. If you want to do your own subjective testing, here are some things you must consider.

Define a Reasonable Scope and a Testing Procedure

Decide if this is going to be an autocross or road course test right off the bat.  Either are doable, but they take differing amounts of logistics and budgets.  Road courses, despite being expensive are actually a little easier as they can be more consistent. 

First off, set boundaries and limit the scope of your testing. Do some research ahead of time to narrow down the field of tires and start that with what your competitors are using. A team of two people can typically test four different sets of tires on a single car with a day of autocross track time, assuming that both drivers are already comfortable in the car and the track layout. Figure on five or six runs for each driver on a set of tires.

 

Tire tests are helpful to figure out what tire you should run this season—little changes in compounding like Hankook did between the RS3 and RS3 V2 can make a big difference in lap times. 
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Comments
Nick B
Nick Blink
Friday, January 16, 2015 7:13 AM
What about variables like the amount of fuel in your tank throughout the day? Is there enough weight to make it a concern?
Per Schroeder
Per Schroederlink
Friday, January 16, 2015 7:19 AM
Good question...It depends on how many sets you're doing--typically with 2-3 sets of tires on an autocross course, the gallon or so of fuel you'll typically burn during that sequence won't mean much….a passing cloud and resulting pavement temperature change will affect things more.

That said, if you're on a road course, the fuel weight will vary more and you should top up or monitor for every session.
buzzboy
buzzboylink
Friday, January 16, 2015 2:28 PM
Most of our tire testing has been, "Will it hold up to a full race(14.5hrs)?" Being confined to a 205/70/14 meant we didn't have any performance options so we were picking the tire that would last the longest. The car weighs 3500lbs in race trim without much front camber possible. It munches front tires.

We've finally found some better wheels so in 3 weeks we get to truly have our first "test" with some 225/50/16 Direzza ZIIs. It will be exciting to race with a proper tires for the first time. Then we can start thinking about trying different brands and styles.
Rockwood
Rockwoodlink
Tuesday, January 20, 2015 10:54 AM
@ buzzboy: what car are you driving? 3500lbs on 205s sounds frustrating...
Rockwood
Rockwoodlink
Tuesday, January 20, 2015 10:56 AM
@ Per: some tires need more/less tire pressure, and others prefer different alignment settings to really shine. Got a version 2.0 coming for figuring out these variables? :)
Per Schroeder
Per Schroederlink
Tuesday, January 20, 2015 11:02 AM
Working on it!
buzzboy
buzzboylink
Tuesday, January 20, 2015 1:28 PM
@Rockwood
It's a '79 Mercedes 300SD. The stock wheels are 14x6 so the tire options are quite limited and the stock wheels are et 22 so it's difficult finding modern wheels that don't hit suspension parts. Driving around the track was interesting. When we tried normal tire pressures the sidewalls flexed over and the tires chunked. We were running 50psi hot in the front to stop the sidewall from rolling over in the following races. 1000lbs of engine/transmission make it a front heavy pig at times.
Rockwood
Rockwoodlink
Tuesday, January 20, 2015 1:57 PM
Lemons?

Why not use wheel spacers?
buzzboy
buzzboylink
Tuesday, January 20, 2015 2:01 PM
Yep.

The quality of spacer we'd want to race with are ~100$ per corner where the CLK wheels we just bought were 50$ per corner. They should do fine.
Rockwood
Rockwoodlink
Tuesday, January 20, 2015 2:10 PM
Ah, didn't see you had wheels that worked.

Should be able to redgineer (redneck engineer) some more camber into it. It's lemons!
leslie reid
leslie reidlink
Friday, February 27, 2015 5:48 AM
Thank you Schroeder for sharing such valuable info with us. Procedure you have illustrated is very nice and really admirable. My car wheels are new and I am so concern about its caring. This procedure is surely going to help me out on testing.
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