Question about HPP3
Question about HPP3 Hi guys, I have an '01 3.8L Camaro and I'm planning on putting C5 wheels on it. I was wondering if the HPP3 lets you set different tire sizes for front and rear because I was going to go with the 17x8.5's for fronts and 18x9.5's for the rears. If it doesn't let you input two different sizes, are there any programmers that do and if not, what would you guys set it at for that setup? Thanks.
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
you can't change bias front and rear... however the size of the rim doesn't mean anything... it's the overall diameter of the tire... if they're different (front to back) then you'll get some ABS codes
If the rear are a different height then stock, then you'll have an incorrect speedo and in that case yes an HPP3 can fix that ... though may be cheaper (if you're not going to be making many more tire heigh changes and such) to just have TSP or thunder do a tune.
What's the new tire height?
To calculate tire height:
225/60/16 for example is a typical tire reading
225/25.4 = 8.86" which would be the tire width
60 is the aspect ratio, meaning 1 sidewall is 60% the width
so .6 * 8.86 = 5.315
2 sidewalls so 2 * 5.315 = 10.630
+ the wheel diameter (which is the 16 portion)
16 + 10.630=26.630 height
so just calculate the height now, and then the new height, if there's a big difference you'll need the PCM updated to reflect correct speedo... if it's minor then no worries
If the rear are a different height then stock, then you'll have an incorrect speedo and in that case yes an HPP3 can fix that ... though may be cheaper (if you're not going to be making many more tire heigh changes and such) to just have TSP or thunder do a tune.
What's the new tire height?
To calculate tire height:
225/60/16 for example is a typical tire reading
225/25.4 = 8.86" which would be the tire width
60 is the aspect ratio, meaning 1 sidewall is 60% the width
so .6 * 8.86 = 5.315
2 sidewalls so 2 * 5.315 = 10.630
+ the wheel diameter (which is the 16 portion)
16 + 10.630=26.630 height
so just calculate the height now, and then the new height, if there's a big difference you'll need the PCM updated to reflect correct speedo... if it's minor then no worries
