Gas Mileage tricks for cruisers with 35" tires? (1 Viewer)

[Randy88FJ62]

What type of mileage do people get with 35” tires? (Especially those who are sprung over and have 4.88’s.) In the last few months my best mileage has been 13 mpg drafting a friend’s motor home going about 60 mph at around 2,000 RPM’s. The second I get up to about 70-75 mph doing 3,300 RPM’s I get around 9 mpg. I don’t expect these iron pigs to get awesome gas mileage but I would like to confirm that this is normal. Not being able to get 10 mpg doing 65 mph at about 2,800 RPM’s is annoying.

Does anyone have tips to increase gas mileage by 1 to 2 mpg? I would like to get around 12 mpg consistently. Would sending my injectors out for cleaning help at all? Cooling system is in good shape, fuel pump and fuel filter are 3 yrs old, fuel pressure regulator is new, axles have been rebuilt and all bearings in good shape, and plugs and wires are 3 years old.

 

[GLTHFJ60]

Lower gears or better overdrive. 3300 rpm's is excessive for cruising speed. I cruise at 2500 rpm's at 70 with 35's and 4.11's, but the overdrive on my H55 is less than your A440 I believe. I get 12 mpg everywhere I go.

 

[landcruiserjunky]

13mpg on a good summer day, 9mpg during the winter rocking out 35s, stock gears (fj60)

 

[RockDoc]

Those engine speeds aren't all in OD are they? If you are doing 2000 rpm at 60, you should only be doing 2500 rpm at 75 if the lock up is working.

 

[jbeck53]

Im still sua but with about 5" of lift. 315s that measure about 35.5 inches and 4.88 gears. I get 9-11 mixed driving. If there are any hints, id love to know them. haha.

 

[Randy88FJ62]

Those engine speeds aren't all in OD are they? If you are doing 2000 rpm at 60, you should only be doing 2500 rpm at 75 if the lock up is working.

Rocdoc,
You may be right about the trany. It is still having intermittent overheating during long drives fully loaded up grades. I can count the shifts and see the rpms drop into 4th when driving. Still need to diagnose it properly but I'm not sure how much more I can do in the fsm without dropping it.

 

[2mbb]

I have 33x12.5 with 4.56's and an H55F. At 3000 rpm I'm somewhere near 70mph. I get something like 11mpg. I remember days when I would get 14, but that was with stock drive train and 31x10.5(?) tires. I don't know if (1) my truck is getting tired, (2) it's the bigger/wider/heavier tires, (3) it's the lower overall gear ratio or a combination of all three. You should also be aware that the faster you go, the more energy you expend pushing the air out of the way. There is a big differece between 55mph and 70mph, all other things being considered (doubling the speed, quadruples the wind resistance)

 

[Randy88FJ62]

I have 33x12.5 with 4.56's and an H55F. At 3000 rpm I'm somewhere near 70mph. I get something like 11mpg. I remember days when I would get 14, but that was with stock drive train and 31x10.5(?) tires. I don't know if (1) my truck is getting tired, (2) it's the bigger/wider/heavier tires, (3) it's the lower overall gear ratio or a combination of all three. You should also be aware that the faster you go, the more energy you expend pushing the air out of the way. There is a big differece between 55mph and 70mph, all other things being considered (doubling the speed, quadruples the wind resistance)

It's soo hard to be patient and do 55 to 60 everywhere. I definitely see a huge drop in fuel economy when doing 70 to 75...

 

[Michael Hanson]

Try to keep the rpms around 2,000. Up to 17 mpg on occasion. MIke

 

[Elbert]

never got over approx 13mpg when truck was stock. Your not going to get any mpg at those RPM's

 

[lonelydriver]

Randy, have you tried advancing your timing a little? I'm getting about 12mpg on average, city/highway mix driving at about 60-65 on the freeway with engine buzzing at 2800-3k. my engine is not running properly and i get some pinging if i give too much gas, but if i do mostly highway and slow to about 55-60ish i think i can get 13mpg mayyyyybe 14 with the wind pushing me.

Not sure if I recall but dont you have a rack on your roof? that would hurt the mileage a bit too.

Kevin

 

[cruiser88]

advance 10 or 12 degrees or get a4/ 5 speed

 

[Randy88FJ62]

It looks like my problem is my lead foot. Thanks for the quick survey.

 

[hjdca]

My cruiser has 31's on it, but, I have found that people that live in "flat states" always claim good gas mileage on this site, and people that live where there are alot of hills always claim bad gas mileage... I live outside LA and there are grades everywhere on the fwy... Every car I every bought always did much worse on mileage than it was supposed to.... The cruiser is worse, because it does not have alot of horse and it has bad aerodynamics, so, you have the hammer down climbing the grades...

 

[lehiguy]

Without a trailer or a lead foot, 15 MPG with SOA, 4.56 gears, TBI 350.

 

[Randy88FJ62]

Without a trailer or a lead foot, 15 MPG with SOA, 4.56 gears, TBI 350.

No TBI 350's allowed, that doesn't count. I'm talking stock engines. Wish I had the time to put an engine like that in right now.

 

[stocksail]

#1 mileage tip: Don't have it as your DD.

I'm sprung over with 35"'s and stock gears and run around 2400rpm at highway speeds (my speedo is off but I think I'm doing between 63 and 68 mph) I get +/- 13mpg.

Lower speeds are better for me because of the HUGE drag coef. SO these things put up. I think at 70 I make the semi's sway ;p

 

[worldspan]

advance 10 or 12 degrees or get a4/ 5 speed

Will this also work for a desmogged FJ60 with 33's?

whats recommended timing for a desmog anyways?

 

[MANUCHAO]

No TBI 350's allowed, that doesn't count. I'm talking stock engines. Wish I had the time to put an engine like that in right now.

Being that you have a heavy led foot.. its prob.... best you stay with the stock engine

I dont think an engine swap will help yah much

 

[lehiguy]

I feel so... rejected.