Tire size question?

[JoKKer]

Just a quick question, I have a 98 Sport 2WD. I don’t do a lot of off road except at the beaches here in Florida. Here where I’m at I can still drive on the beach. Anyway, just wanted to ask a couple of questions. I wanted to go with a 30x9.50x15, but I was looking and the 275x70x15 looks like it’s the same size. I’m wanting to bigger without messing up the speedo or having to regear it.

I don’t want to go with the 31’s. That is just my preference. Can anyone give me some advice? I’m looking to get tires in the next week or so.

Thanks in Advance, Chris.

 

[Dan Whitaker]

Chris, I would go with the 30x9.50x15. These are what they call a "floatation tire" the wider the tire on sand the better as it will float on top instead of digging dowm in the sand. The 30x9.50x15 wont mess up your speedometer to bad. I would say it would be off maybe two- three miles an hour. If your speedo says 65 you will actuly be going 68. Hell on my 97 Mountaineer with 235x75x15s it was going slower than the speedo said and now with 30x9.50x15 BFG AT KOs it is right on.

 

[ChuckyD]

275/70 15 is 10.8" wide and 30.1" tall
a 31 x 10.5 is usually 30.5 inches tall
stock is about 28.9 " tall

 

[JoKKer]

Thanks...

Thank you very much guys that was huge help. Thanks for the info.

 

[Dan Whitaker]

That's what we're here for

 

[ChuckyD]

I dont konw what your talking about, dan. Im here for the food

 

[NoBoundaries]

I wouldn't worry about your speedometer incorrectly displaying your speed. The 255/70R16 is about the same height as what you are looking at and it comes standard on Explorers with 16" wheels. I went from a 235/75R15 to a 265/75R16 (32") and there really isn’t any noticeable inaccuracy in the speedometer. I am sure all Explorers are gauged the same from the factory, whether they come with 235/75R15's or 255/70R16's.

Just wanted to make a note of this so you didn't have to worry about getting your speedometer recalibrated.

 

[JoKKer]

recalibrated?

Why would I do that I just keep up with traffic. I don't pay attention to speed limits unless i'm in a residential neighborhood. Anyway thanks for the advice.

 

[Robert]

Originally posted by NoBoundaries
I wouldn't worry about your speedometer incorrectly displaying your speed. The 255/70R16 is about the same height as what you are looking at and it comes standard on Explorers with 16" wheels. I went from a 235/75R15 to a 265/75R16 (32") and there really isn’t any noticeable inaccuracy in the speedometer. I am sure all Explorers are gauged the same from the factory, whether they come with 235/75R15's or 255/70R16's.

Just wanted to make a note of this so you didn't have to worry about getting your speedometer recalibrated.

All Explorers' speedometers are calibrated to the tires/transmission/rear axle ratio. That is why Ford uses several different speedometer gears in there. The newer ones it is done through the computer though. Going from a 235 75R15 tire to a 255 70R16 tire will make your speedometer read 5.5% slower at all speeds. Your change wasn't that drastic so when your speedometer reads 70 MPH you are actually going 73.8 MPH (this assumes your speedometer was accurate to begin with). Since the Ford speedometer gear centers around 20 teeth, changeing it by 1 tooth will alter your speedometer by about 5%. In your case if you got a new gear with 1 less tooth than the one in your Explorer your speedometer would be more accurate.