Tire Size vs. Mileage Question

[rsteffen]

I am thinking of upgrading my truck with a Kore or DRC suspension kit and 35 x 12. 5's. I understand that the larger tires will lower my engine RPM at speed, but the size and weight will put more load on the engine. What is the overall outcome? How bad is this gonna kill my mileage?





I hope that this question hasn't been answered already. I searched the forums but didn't find anything.

 

[Coolslice]

I am thinking of upgrading my truck with a Kore or DRC suspension kit and 35 x 12. 5's. I understand that the larger tires will lower my engine RPM at speed, but the size and weight will put more load on the engine. What is the overall outcome? How bad is this gonna kill my mileage?





I hope that this question hasn't been answered already. I searched the forums but didn't find anything.

I just dealt with this issue a month or so ago with that setup on my truck. . I would give you a link, but I can't find it either. :-laf



I have the 48re and 3. 73 gears. IMO the 35's are no good with that setup at all. It bogs the engine something awful unless you're doing 75 mph. My mileage went from about 18. 8 hwy to 14. 8 hwy. I seemed to have experienced much more mpg loss than others have reported, but it is possible, I can assure you. . I would have kept everything despite, if I had 4. 10's and (or) a 6 spd. . I'm not sure what gears/ transmission you have, but if you have what I did, I would not advise it. If you're doing it for looks, I don't think it's worth it. If you NEED the extra tire size, then obviously it is. .

 

[Scrappy]

mileage

I have 35/12. 5R17 BFG's on mine, I put them on because I bought a truck w/4. 10's. Around town on short trips I get around 16 mpg's, If I keep it between 45 and 60 on longer trips it will get around 20mpg. of course it drops below 15 on the interstate running 70+. the 35's basically brought my overall ratio around what 3. 73's with the stock tires.

 

[akshadow]

I am thinking of upgrading my truck with a Kore or DRC suspension kit and 35 x 12. 5's. I understand that the larger tires will lower my engine RPM at speed, but the size and weight will put more load on the engine. What is the overall outcome? How bad is this gonna kill my mileage?



I did not change tires size but when I had the CHASE system installed my freeway/highway mileage decreased approximately 1 mile per gallon. Around town their was virtually no change. I assume this is because at low speeds the increase height of the truck and related air disturbance is not an issue, the main factor at low speeds is weight of rig especially in stop and go.

 

[JVolpe]

I have 2" leveling kit and BFG 315s, 48re and 3. 73 gear. I lost 1-1. 5mpg city driving. I lost very little mpg highway if any. The higher you take the overall profile the more your going to loose on the highway. I don't have any issues with power or responiveness, but I have my Juice on 80hp all the time now.

 

[JCleary]

I am thinking of upgrading my truck with a Kore or DRC suspension kit and 35 x 12. 5's. I understand that the larger tires will lower my engine RPM at speed, but the size and weight will put more load on the engine. What is the overall outcome? How bad is this gonna kill my mileage?



I did not change tires size but when I had the CHASE system installed my freeway/highway mileage decreased approximately 1 mile per gallon. Around town their was virtually no change. I assume this is because at low speeds the increase height of the truck and related air disturbance is not an issue, the main factor at low speeds is weight of rig especially in stop and go.

I experienced about the same results with the same suspension running 285's. I had the 285's before and after, and lost about . 5 to 1 mpg. It may be due to the new exhaust and intake I added at the same time, hard to tell.



When I switched from 285's to 35's, my around town mileage dropped from 15-16 or so to 14 or so, depending on how many lights I hit.



Highway mileage still seems to be around 17. 5 at 75mph average, not too bad, and that's hand-calc with the Quad on 60.



My best mileage was at about 10k miles, 600 miles in one day with a stock truck, 70mph average, 19. 5 hand-calc.



Never could duplicate that.



Overall I'm happy that I can drive around in a 7k+ pound truck that accelerates like a sports car and still get 17 or better mpg. Show me a gasser that can do that!

 

[NLamke]

I have 35's with 373 gears and the 48RE, and a leveling kit. I would do it again in a heartbeat. LOVE the looks, and is insane off road. Plenty of power stock. Mileage did go down about 1. 5 or 2 mpg. I just got the Juice/Attitude combo but haven't been able to do any mileage checks as I promtly blew my intercooler up. Got it back today though, and with a metal intercooler too! Early guess on mileage is that I gained with the chip what I lost with the tires.

 

[rbattelle]

Here's that excellent thread from Coolslice. A real learning experience.



-Ryan

 

[sarj]

truck: 315's w/ kore, auto w/ 3. 73

mileage before tires/susp. (600 miles): 18. 8 on a highway drive home from picking up the truck

After tires/susp:

mileage preflash: town-14, highway 16. 5-17. 5 depending on speed.

milege post TSB flash- 16. 5 town, 18. 5- 21. 8, depending on speed. 18. 5 was 75-80 mph. . the 21. 8 was rolling hills at 60 mph at 3000 to 5000 feet elevation.



drivability- very pleased. Obviously you lose a little acceleration, you also lose a little braking ability. Towing- I only pull 5K and run 1600 & 1700 rpm at 60 & 65 mph. It pulls like it's not even there. In town handling: greatly improved. Offroad- very high confidence level.



opinion- for my type of driving, I'd buy the exact same truck, and set it up the exact same way... no hesitation. good luck



sarj