1990 C4 18” Track tires recommendations
03-19-2018, 02:37 PM
#1
Advanced
Thread Starter
1990 C4 18” Track tires recommendations
Hello all,
Hello all.
I know tires sizes have been covered ad nauseam for our cars, but less so for 18” and for track use. I feel I have made a mistake and bought the wrong tires for my C4. I run 18x8 and 18x10 E88s with MPSS tires 235/40/18 and 265/40/18 respectively on the street/track. I find at high speed over 75mph and sometimes on hard deceleration the yellow interlock light on the lower console lights up and the car will push unexpectedly. As you can imagine this is unnerving and dangerous . I am wondering if the tires sizes are incorrect as this never happened with my 16’ phone dials. The diameter of the tires are the same at 26.3”. Is that out of the normal operating range for the all wheel drive system/PDAS? I guess buying new tires is not all that bad just would like to use the cash for other items or track days.
P.S Just want to thank all of the great posters on this website who have helped me enjoy and fix this wonderful car.
Have a wonderful day everyone!
Hello all.
I know tires sizes have been covered ad nauseam for our cars, but less so for 18” and for track use. I feel I have made a mistake and bought the wrong tires for my C4. I run 18x8 and 18x10 E88s with MPSS tires 235/40/18 and 265/40/18 respectively on the street/track. I find at high speed over 75mph and sometimes on hard deceleration the yellow interlock light on the lower console lights up and the car will push unexpectedly. As you can imagine this is unnerving and dangerous . I am wondering if the tires sizes are incorrect as this never happened with my 16’ phone dials. The diameter of the tires are the same at 26.3”. Is that out of the normal operating range for the all wheel drive system/PDAS? I guess buying new tires is not all that bad just would like to use the cash for other items or track days.
P.S Just want to thank all of the great posters on this website who have helped me enjoy and fix this wonderful car.
Have a wonderful day everyone!
03-19-2018, 07:05 PM
#3
Rennlist Member
interesting. so do the overall diameter of the MPSS match the previous tires?
MPSS are grippy, but what were you using before?
How is your rear diff? LSD?
MPSS are grippy, but what were you using before?
How is your rear diff? LSD?
03-19-2018, 07:36 PM
#4
Rennlist Member
The issue he is having is with tired dia. You should be using as Koenig said and with 225/340/18 (25.4") and 265/35/18 (25.3"). Instead of the 235 up front in a 40 profile 26.3" dia.
03-19-2018, 08:26 PM
#5
Rennlist Member
++^^^ Actual tire diameter is critical in the C4. That's why some of the performance tire options are limited. Use a tire diameter calculator against the original stock sizes to compare where you are. If you're not bang-on in equal diameters the car will struggle with you and you'll get PDAS issues. This can be temporarily stopped when you press the brake pedal. Have you noticed this?
03-19-2018, 10:26 PM
#6
Advanced
Thread Starter
Thanks for the input everyone. I thought it might be my overall tire diameter as this did not occur with my stock 16’ wheel/tires. Lesson learned. Now to find someone who will use my old tires and order the correct sizes. Will put them in the parts marketplace if any of the C2 guys/gals are interested. Have a wonderful evening everyone.
-Matt
-Matt