Here's the Big Brother and the Holding Company version, from Grateful Dead Lyric And Song Finder, a far more reliable source:

I'll Change Your Flat Tire Merle

Lyrics: Nick Gravenites
Music: Nick Gravenites

Played by Jerry Garcia with Nick Gravenites and Pete Sears on 29 Apr 1990. A riposte to Merle Haggard's "Okie From Muskogee". Not yet checked against a tape: this is the Big Brother version:




I'LL CHANGE YOUR FLAT TIRE, MERLE
(Nick Gravenites)

I was cruisn' down old 99
Speeding down the old Grapevine
Must have been doing about ninety five
Well I saw a new car all broken down
And who do you think was a-standing around
But the greatest country singer alive

CHORUS
Oh I'll change your flat tire, Merle
Don't you get your sweet country picking fingers
All covered with oil
You're a honky I know, but Merle, you got soul
So I'll change your flat tire, Merle

Well I heard about them records you did
Putting down all them long-haired kids
For saying what they're feeling and how they think
Well it's hard to make a world your own
And if you have to go out and get stoned
It's better with a joint than a drink

CHORUS

I heard you had an adventurous youth
Camping out in a telephone booth
I even heard you spent some time in jail
But now you've got a brand new car
Brand new ranch house with a bar
Picking up your cheques in the mail

CHORUS
CHORUS


Recordings
Nick Gravenites recorded this with Big Brother And The Holding Company on "Be A Brother" (1970), and it was covered by Pure Prairie League on "Two Lane Highway" as well as on the live album "Live Takin' The Stage"

Further Information
For more information on recordings see Matt Schofield's Grateful Dead Family Discography


Source: http://www3.clearlight.com/~acsa/introjs.htm?/~acsa/songfile/I2LLCHAN.HTM

Nick Gravenites replaced Janis Joplin as lead singer in Big Brother and the Holding Company.

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Cultural note: The Grapevine is the highway across Tejon Pass, separating Bakersfield from Los Angeles, CA. The highway has been designated U.S. 99, California Highway 99, and Interstate 5. The Grapevine has some of the most spectacular views in California, but it's a very dangerous place to have a flat tire.
Merle Ronald Haggard was born April 6, 1937, in Oildale, a suburb just across the Kern River from Bakersfield. Alvis Edgar Owens, Jr. (August 12, 1929 – March 25, 2006), better known as Buck Owens, was born in Texas and died in Bakersfield. Buck Owens had his headquarters in an old theater in Oildale.