Gday all.
Been awhile since ive posted but ive been in the background learning alot about Blazers from all the different threads.
My question is what size tyres are ya'll running? & has bigger tyres affected
your fuel economy? Ive just put 31/10.5/15 tyres on my Blazer & it seems like its drinkin twice az much fuel as it used to now

 

What gear ratio is your truck equipped with? If it's the GU6 3.42 gear ratio then the 31s will definitely be worse on fuel. Especially if you drive mostly stop and go city style. 3.73 gears (RPO GT4) would be a better match. I do about 75% highway driving and my economy went up a tiny bit, but your driving style will definitely affect economy as well.

 

ive got no idea mate. i know its just the standard factory diff for the LS 4.3ltr.
ill be jacking it up tomorrow & seeing what ratio is in it tho. Cheers for the info in what to look for.
Being in Australia, makes it hard to source parts for it unfortunatly but ill see what i can sort

 

Does Australia use RPO codes? If so, the code to tell you what gear ratio you have will be on a sticker in the glove box. Most likely the gears in your truck will be one of these:
- GU6 - 3.42
- GT4 - 3.73
- GT5 - 4.10
- GU4 - 3.08
As far as I have been able to research, those are the gears that came from factory on the S-series trucks and SUV's. By far the most common were the GU6 and GT4 gears.

 

Theres a sticker in the glove box with the VIN number & a big list of different codes on it.
i can see it has GT4 & G80 listed. i think this is the sticker you mean as the car was imported from over there


16930970_10210592112992087_480197025_o.jpg

 

Your odometer and speedometer is now running about 8% less than you are actually diving because of the larger tire. If that's how you are compairing milage then add 8% to your fiqure. You have the best gears and posi traction so that's good. The taller height putting you up in the wind and heavy tires will hurt. You should be OK.