Finally got the other Hoosier delivered late Thu. Had them both mounted and balanced today. Got home and found the mechanic gouged my paint near the valve stem (see tire on left below). Grrrh! Called them up and they want me to bring it in so they can see it.
So, I really want to see how these 26" babies feel and test whether Stabilitrak or ABS will complain.
First things first... Let the sun warm them up (80 F today). Then aired them up to max pressure (44 PSI) and measured their circumference. Then drop to operating pressure and measured again. Final measurement should have both at the same circumference. I don't have a soft tape measure for some reason so I used stout twine and my Stanley tape measure, marking each measurement with felt markers.
Everything I used is pictured here:
So I mark the start point on the string. Then I wrap it around the middle, making sure it's straight, and mark the other end of the string where it lines up with the first mark. Repeat for the other tire. Then I aired down to 21 PSI and measured both again.
Now I have 3 marks.
I got my grandson to help measure
At 44 PSI left measured 81 5/16" and right measured 81 9/16". At minimum of 21 PSI both measured 81 1/8". Perfect!
Time to install them and go for a ride...
First, let me point out that my painted wheels came with fully painted lugs. Both had paint in the bevels - not good for proper torque. I'd recommend scraping and sanding off all paint from the lug mating surfaces.
Here's my wheel R&R tools:
Air and battery 1/2" drive impact wrenches. 2" HD extension, 3/4" and 7/8" impact sockets, 50-250 lb ft torque wrench, TPMS learn tool, dial-indicator pressure guage, air fill hose, abrasive pad for cleaning lug mating surfaces, and my trusty pocket journal. (not shown: aluminum racing jack & air tank).
Okay, so the last thing to do is "re-learn" the TPMS so it knows I've got 2 new tires. Unfortunately, GM didn't see fit to give us the ability to record more then 1 set at a time. If you don't do this you'll get pesky warnings and your tire pressure readings in the DIC will be wrong.
1. For my M6 to power up without starting the motor I hold the start button for several seconds. You can do this with the motor off or on.
2. From the Info menu press your up-arrow 2 times to show the tire pressure display.
3. Hold down [SEL] button for 3-sec until you hear a double horn-beep.
4. For each wheel starting with left (driver side) front, position the tool resting on the rim while pointing the antenna toward the valve stem. Then press and hold the button until you hear a single beep.
5. Repeat for each tire in this sequence: right-front, right-rear, left-rear
6. There will be a pause after the single beep on the last tire. Then you'll hear two beeps again, indicating success.
Now, I'm finally ready to try and burn those nubs off. I think the Hoosiers look fabulous!
Because I only use these at the track, I put the car in "Track" mode with TPM mode "Race". I warmed it up and took it out on the highway.
Wow! I really can't make it spin the tires on asphalt no matter what I do.
Rev limiter activates at 61 MPH (6600 RPM) on the speedo in 1st gear now instead of 63. I think the actual speed was probably 58 or less. It does seem to accelerate more quickly with the shorter tires too.
Only warnings I got were the familiar low tire pressure warnings. No complaints from Stabilitrak, ABS, or any other systems.
The only problem I had was when I lowered my racing jack after installing the DRs. I had it centered behind the car, lifting on the diff case. When it came back down it touched the muffler and pushed it up a bit. Next time I'll have to come in at an angle.
--Cal