I was up in air on new tires. I came to Goodyear Triple Tread, Grabber HTS, & Avon TSE, in order, for my picks. Grabber UHP was a choice, but I need dry/wet/ snow; so I chucked it out.

255/70/16 is orig. size. I could stay w/ that all around. Americraps were terrible traction in rain; I didn't like in snow either. Dry traction gets worse w/ wear.

Sooo, thinkin 255/70/16 frts, & put 275/60/16 rears.

-255/70 - 30.1" diameter.
-275/60 - 31.2". <-----this should say 275/70/16.EDIT 6/4/09.

3.42 gears.
I checked HPT FAQ's, forum, & here. Is it possible to change thru HPT w/ accuracy? If so, how is it done?
It looks to me that a rollout method is used. Can someone help out on pluggin in numbers/ tips so I can understand better?

 

Open editor, go to speedo, click on speedometer, enter new tire size, click commit, save, etc.

 

Make sure "auto scale transmission tables" is "on" and dont forget to enter your rear-end ratio. Also there is a very useful tire size calculator under "Tool">"Unit conversion"

 

275/60 16's are 28.99" tall; not 31.2. Really you wouldn't have to change the speedo at all; my stock tune actually had 28.9" for the stock tire size.

 

Thanks for all replies; any other hints?

StrokerAce03, my bad. I meant to say 275/70/16 in back, that is 31.2".
I'm hoping the tire being 1.1" in back will help out w/ smoothing out the ride, since it rides a tad harder since the TVS/ drop. The main thing is new tires.
And a bigger contact patch.

Does anyone have pics of staggered tire size as I listed?
255/70/16 Front, 275/70/16 Rear. A shot from the rear, side & a 3/4 rear for an idea? But any would let me see. Oh, on a RCSB would be the ****.

BTW, 275/60/16 would look beefy. But @ 28.99", call it 29", it's puttin me even closer to the ground. Not a good thing where I live. I need ground clearance in snow, shitty roads w/ potholes, & random road kill.

 

Pulled the trigger on some Grabber HTS's.

 

To answer the OP's question, you can enter your new tire size diameter, and it will correct your transmission shifting and speedometer. However, I have not found anywhere to enter a different front tire size diameter. This will create some issues in the ABS system. Possible erronious warning lights, and unwanted ABS activation during normal braking are most likely. You may need to disable the ABS system if you stagger tire diameters.

 

A problem w/ the ABS isn't a problem I want to have. I read of some on HPT forum said no problems on their combo, while others had to work it out. Another would shut ABS lites & such off only to do again. I hope it doesn't appear at all, but I certainly don't want to do every time I start truck. Like some F-bodies do where they switch off TCS or whatnot by overriding manually or automatically thru a switch like SLP makes to do on F-cars.

 

Unless you disable the ABS, you will have the problems. The EBCM will see the front tires and rear tires rolling at different speeds.

 

If a person runs plus sizing on tires, it refers to say, for example, runnin some 17"s & 18"s or a 18/19" combo. When that occurs, I gotta think someone goes thru what I may be facing. They must tune for it.
According to a friend, u may be able to have the engine/ tranny tuned, but not the ABS.

I thought bout what he said thereafter.

And came up w/ this. From the factory, they use a 17/18" on say a C5 Z06, then later Z06 years, they went to a 18/19", both Z06 setups were engineered for their seups. And therefore, the programming written to include for those tire/wheel combos. That which the ABS would be setup for properly (from the factory).

I'm no engineer, but somebody had to write that ABS/ programming for plus size tires for GM. So someone or a group can do it. No, it wasn't me. I'm hoping I can figure it out.