factory 225/70/15 to taller tires?

[erik2282]

I was thinkin about maybe getting some taller tires when its time to throw these away. If I got like 225/75/15's or 235/75/15's would it give a lit bit better gas mileage since the tire is a little bit taller? Im not looking for tough lookin or aggressive tires just something that will help a little in mpg's.

thanks
erik

 

[Sunk]

What kind of mileage you will get depends a lot on what gears you have, how you drive, and where you drive. If you go a little bigger and you don't have gears that will turn them and keep your engine in its powerband then your mileage will decrease. Mine came with 215/75/15s and I went up to 31a, and my mileage went down quite a bit. I have 3.73 gears.

 

[erik2282]

I dont know what gears I have. How do I find out? I drive my truck to and from work 5 days a week and dont go out much on the weekends. I dont drive it hard, just normal street and highway. my truck has the 3.0Lv6 and auto transmission. thanks for the replay, Sunk.

 

[4x4junkie]

I dont know what gears I have. How do I find out?

http://www.therangerstation.com/tech_library/Axles.html

As Sunk mentions, bigger tires may not help (it's actually possible for SMALLER tires to help, but it again depends on what gear ratio you have.

On a stock unlifted truck, you'll want to be shooting for around 2500-2700RPM in overdrive at 60 MPH for best MPG on a 3.0L V6 (a tad higher RPM if the truck is lifted).

 

[erik2282]

i forgot to mention that my truck is 2wheel drive. i checked the tag and it says 3.73 for the gears. so tires that are justa tad taller will hurt my gas mileage? even if they're just an inch or so taller? i'd think they would help alittle. i used to have a chevy s10 with 215/75/15(stock, which is about 27" tall) . I later put 245/40/18's(about 24" tall) and the speedometer would say 60 when I was really going about 53 or 54. So I'm kinda reversing that in my head if I got taller tires if you know what i mean. Does that make sense to you guys? thanks alot for your responses guys. really appreciate it....

 

[4x4junkie]

2WD/4x4 doesn't matter, it's about the engine RPM cruising at highway speed.

With 3.73, I would say in the best case, your MPG will not change, you're pretty close to what's ideal with that and a 27-28" or so tire. You'll lose a bit of oomph to the bigger tires though.
Remember that a WIDER tire (taller or not) will hurt your MPG also (more rolling resistance).

How fast do you drive? (what MPG you getting now?) You'll easily get 2-3 MPG more just by going 60MPH instead of 75.
Also, the engine's state of tune will impact it tremendously, too.

 

[erik2282]

i drive at about the speed limit. I dont dog my truck or anything, you know... I drive it pretty smooth, dont mash on the accelerator or nothin like that. I want my truck to last a long time so I try to take very good care of it, as I've done with all my vehicles in the past. my '00 ranger has 58K miles, I havnt had it even for 2 weeks. But so far I've done maintenance service on it just so it'll be tip top. I did the mercon v service with filter and pan gasket, drive belt, valvoline 5w30 oil change with motorcraft filter, engine air filter, replaced two lower ball joints and aligned, pcv valve, and front wagner brake pads and cut rotors. I did all the work myself with the exception of the ball joints/alignment. i got the spark plugs/wires, just havnt put them in yet... the truck is running really good actually...

 

[4x4junkie]

I'd just keep the same size tires you have now. There's no real good reason to go bigger unless you're after more clearance for offroad use.

Don't forget to change the fuel filter and engine coolant as well.

 

[erik2282]

oh yeah, I did the fuel filter too...

hey thanks a lot, 4X4.