Thinking about 16" tires

[hat_man]

Hello everyone,

My '97 Ranger has stock 14" tires on it currently and they have a lot of life left. A good friend has a set of 16's on Ford rims that he would consider selling me very cheap. I have heard that this swap would change my final drive ratio for the good, but I am wondering about the spedometer. Approx. how much would this throw off my spedometer? If it's only 1-2 mph then I'm not going to worry about it, but if it's a substantial difference then is it really worth having the spedo recalibrated just for a small savings at the pump. The 16's would much better fill the wheel arch area and cut down on the massive gap between the tires and the fenders. Any advice is greatly appreciated. Thanks.

[mcrews]

there are numerous posts on this topic try searching.

[almightybmw]

Won't help. Metal weighs more that rubber doesn't it? You're making a 14" diameter by 6" wide steel or aluminum metal band now 16" in diameter, and possibly 7" wide. Some quick math tells you this is heavier. You want weight near the center of rotation, not on the outskirts.

Plus you don't mention what size the tire is. 265/70R16? 195/65R14?
I can pretty much tell you it's a bad idea, don't do it. Do some searching for the ALL reasons why bigger rims and bigger tires are bad.

[abell75]

To answer the question:

Yes, your speedometer will be wrong. (I know this math is not quite right, but it's close). It will read LOW by a percentage approximately equal to the increase in circumference of your tires: 2/14= 14%

So when going 57, you will see 50 on your gage
When going 114, you will see 100

Like others have said, there are many topics posted already. Opinions are mixed; some say the added rotational inertia cancels out the improved final drive ratio, others have positive results.

like almighty bmw stated, you need the circumference of the TIRE not the wheel, to make the calculation.

[jamesqf]

Originally Posted by almightybmw

Won't help. Metal weighs more that rubber doesn't it?

Depends on how thick the metal & rubber are. I don't have numbers, but it seems possible that a larger, lightweight rim could weigh less/have lower rotational inertia that a smaller rim with a heavy tire.

Also, as the OP said, if the tire diameter is larger, it could effectively lower the gearing, which could be an advantage if he does a lot of highway cruising.

Then there's the question of tread width: wider tread means higher rolling resistance.

[roosterk0031]

Not enough information for anything more than wild guess. If the new tire & wheel assembley weighs less but is the exacty same diameter maybe a slight gain in mpg. If your new tire wheel assembly is a larger diameter, you might gain FE if you drive more highway but your speedo will show lower than actual speed. Way to many variables for any think than a guess.

If the wheels are really cheap like $20 each, keep your eye out for some slightly taller tires than your current tires, say 5-10% ones used would be better, stick them on the rears drive wheels and track your mileage. Most likely the speedo is tranny driven so it will show and error. If your mpg seems the same you actually gained.

I don't think you'll save enough $$ justify throwing away good tires. But if price is right and you like the look, find some used rubber and give them a try.

[mcrews]

weight the 16s if there are off.
go to tire rack dot com. look at the diameters on the spec pages for tires.

also what is your current rpm at 60 mph
how much freeway driving do you do?

[euromodder]

You can compare tyre sizes here:

Tire Size Calculator - tire & wheel plus sizing

It'll show the difference in diameter (they still need to fit) and how much the speedo will be off.

[UFO]

Originally Posted by jamesqf

Depends on how thick the metal & rubber are. I don't have numbers, but it seems possible that a larger, lightweight rim could weigh less/have lower rotational inertia that a smaller rim with a heavy tire.

Also, as the OP said, if the tire diameter is larger, it could effectively lower the gearing, which could be an advantage if he does a lot of highway cruising.

Then there's the question of tread width: wider tread means higher rolling resistance.

Invariably the metal in the wheel is heavier than tire sidewalls. And if the tires fit a larger wheel size, the tire sidewalls are even heavier. A smaller wheel with the same diameter tire will almost universally be lighter than a larger wheel, let alone the lower rotational inertia.

[hat_man]

Thanks for all the info. I think I have decided to pass on the tires anyhow. I was hoping to find a way to close the huge opening between the tires and body. Maybe lowering the whole truck 2" would help. I'd still have a bit of forward rake but Ford must have thought it was a good idea. I get pretty good mileage now anyhow. Thanks again.