I just got a 2001 Ford Ranger 2wd with the 2.3liter I4. When we bought it the rear tires really need to be replaced but we're going to do all 4 tires anyway. My father wants to buy stock size tires for it but I think we should upgrade from the 225/70/15s to 245/75/16s. He keeps arguing that there are negative ramifications. Help me convince him otherwise! PLEASE!!! I really can't drive a truck with such tiny tires... it may actually cause me pain lol

if hes paying, then do what he says lol.
if you're paying, then he cant stop you. there will be no "ramifications" just make sure they will fit.

245/75/16's is close to a 31 in size, why not just put 31's on your 15 inch rims? and if you dont have the right gears your truck will struggle to spin a bigger tire.

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1997 chevy 1500 2wd 5.7, air shocks, summit brush guard, bright a$$ strobe light, deep toolbox. Work Trucks: 05 F450 6.0 powerstroke dumptruck - 03 F350 6.0 stake bed - 2005 UD 14foot rollback with air brakes
scraped: 1994 ranger 2.3, auto, cobra cb, wood bumper

We bought the 31 inch Dueler tires for our '91 Silverado a while back and then the transmission went out but we kept the tires. He wants to trade them in if he can and get cheaper small tires but I want to try and save money to pick up some cheap rims off of craigslist or something and put these on. Technically he's paying but I've been told that when I move out (I'm only 16 right now) the truck goes with me. In this scenario pretend it all costs the same..ish
If we upgrade tire size is there a way to adjust the speedo gear or is it a computer thing or what?

Didn't you learn the first time? You put 31-inchers on your Silverado and it caused your transmission to go out! Okay, just kidding :-)

I have 225/70-15's on mine so I understand your dilemma and am having 235/70-15's installed later this week. I too wanted to go much bigger, primarily to fill the wheelwells and gain a larger contact patch, but I decided against it for these reasons:
worse fuel economy
anemic performance
disrupt speedometer
excessive drivetrain wear
insufficient brakes
taller sidewall increases lateral sway and delays lateral inputs
higher center of gravity effects handling, etc...
That being said, if I didn't insist on buying wider rims I might have convinced myself into 255/70-15...they fit 15x7, but I'd only want them on 15x8. Maybe not, I really hate buying gas! It's a scam commodity.

What brand tires are you wanting to get? Aside from the 3" height difference, depending on tire brand I see those larger tires each weigh an additional 8 - 21lbs(!!!). Coupled with the increased rim weight, how slow do you want to go? Maybe your father will compromise on something between your stock size and desired size.

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Oh, regardless of the size you decide on, as you might already know, tires with an aggressively squared tread where it meets the sidewall will appear slightly larger than the same size tire with a more rounded edge.

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1998 Ranger Flareside Reg Cab 2wd
2.5L Lima 4R44E Auto 87,XXX miles 20mpg
Factory Paint Peel Defect
ATC Camper
Yokohama Geolander A/T-S
P235/70R-15