So I have a 1998 Chevrolet Suburban K1500 with a 4 inch trail master lift and 35X12.50 tires. I had 33s on it, and just put on the 35s. I am looking at possibly regearing to 4.30s. I think it has 3.73s in it, but I need to check.
I am looking for advice as to what I need to push forward with. I drive both in town and highway, and I do a decent amount of towing and hauling. I want something with decent performance, but really need to help the mileage as well. Currently, the speedo is about 10% off, and at 70mph it is right under 2000 RPM. I feel like that is too far under the torque curve.
Also, will I need to reprogram my computer? My ABS light is currently on, and I have been told that is due to the larger tires.
Thanks in advance for the help!

 

well, before we can offer any advice, we are going to need some pics of that bad boy...

I had 35s on my Wrangler before I sold it... stopped like a school bus!

 

Basically you are asking for two different things you aren't going to get from the same truck. You want good MPG and good torque for towing with those giant tires. Personally I would be afraid to tow anything real heavy with a lifted truck anyway due to the higher center of gravity and increased chance of squat/sway.

One thing you should certainly do is use a electric trailer brakes whenever towing with this truck. You have much more rotating mass because of the huge tires and that means the brakes on your truck are already working really hard -- especially with the rather wimpy rear drum brakes on the 98.

 

I do not tow huge amounts on a daily basis-but I have been known to take loads to the scrap yard every once in a while or help friends move. I do have a good electronic trailer brake controller, and also have installed Firestone rear airbag assist. I also plan to tackle the brakes at some point, but that is on down the line.
I know that I am not going to get good mileage-I sacrificed that when I got a lifted truck. However, I do believe that I can do better than my current 8 mpg. It has ok power now, but I am just asking around to see if someone who has experience has any suggestions for me.





Those were with the old 33X14s. I have to get pictures of the new 35X12.50s >:]