I drive my Xterra everyday and it now has 50k miles with original tires. Well, they are in need of replacing and I would like to get a smaller tire in hopes of a little better ride and better gas milage while on the highway.

Thanks in Advance..

sorry to tell you it dosent work like that

if you want better hwy mpg you need a larger diameter tire, but you will sacrifice mpg during acceleration + towing ability + torque
you will only get better mpg when cruising at a consistant speed

the other end if smaller diameter tire will get you better mpg during accelaration, more torque and tow ability
but you must sacrifice hwy mpg

no, it would look like you are getting better mpg because the tires will be rotating fasting than normal.. plus it would look just plain weird..

it will also throw off your speedo and odo, neither will be accurate after changing tire size

it will also throw off your speedo and odo, neither will be accurate after changing tire size

keep in mind all of you guys the same goes for upsizing your tires, but it makes your speedo slower than it is and you odo show less than what it really is...

keep in mind all of you guys the same goes for upsizing your tires, but it makes your speedo slower than it is and you odo show less than what it really is...

thats what i have the scanguage for.. LOL MY TIRES ARE 9% bigger than stock....

Jason, how does that help?? I want to get one of them bad boys because I keep hearing about more and more functions they have...

it automatically calculates that 9%(or whatever you put) with your speedo reading, and shows you your true speed, i believe its got a 1-2sec delay but its basically realtime

keep in mind all of you guys the same goes for upsizing your tires, but it makes your speedo slower than it is and you odo show less than what it really is...

That's not true. The ODO stays the same. The odo reads miles on drivetrain,

All the gauges read the same as if all equipment were stock. So if you are running 33" tires as opposed to 31, then your speedo would be off, and you will travel a longer distance than what your odo reads but the ODO is correct on reading every single thing minus tire miles.

i dont know about the new ones with the X-guage but mine has been a life saver.... LOL i would say definantly get one they are worth it...

That's not true. The ODO stays the same. The odo reads miles on drivetrain,

All the gauges read the same as if all equipment were stock. So if you are running 33" tires as opposed to 31, then your speedo would be off, and you will travel a longer distance than what your odo reads but the ODO is correct on reading every single thing minus tire miles.

really.. huh.. i though because you have a larger radius tire it "seems" as if the drivetrain is turning slower than it really is, and if the drive train is turning slower because of the larger tires wouldnt it make the odo read less as well?? maybe i am just missing something..


If a 30" Tire has to rotate 672.2704796 times to travel a mile and a 33" tire has to rotate 611.1549815 times to travel a mile, i did the math and I dont know my point haha, where does the ODO read from??

that is a god ? ? ? ? if the speed is off then so is the odo since essentially it runs by the spedo ( ie.. it is connected and the spedo moves the odo or at least that is what ive been told..... )


also when i run our air machine which is a big truck that acts like a vacuum on steroids, to operate it you put in the PTO to run the hydraulics and when you idle it up to a set rpm's the speed rises and if you watch the ODO it will begin to move just like you were driving down the road...... but that's my 2 cents......

it was so easy back in the cable driven days, you just replace the so many toother gear sensor with one that had more or less teeth, so simple, these days with electronics make everything so hard, I wish I could easily and cheaply recalibrate the speedo/and odo (depending on our findings, if its really off)

I figures bigger tires will help your HWY cruising speed, because the engine is turning less for the amount of distance traveled before.

Bigger wheels will also need more power to turn.

Speedo & Odo will be off if you change tire size or gear ratio.

I was thinking on the way home. I get crappy mileage because I have 4.6:1 gearing, so if I went to smaller gearing 4.10:1 (example) I would get better hwy mileage, but then the xterra would have even LESS power. I dunno, just a thought. lol

I think the only solution would be a lighter weight wheel and a skinnier tire.

that would mean less weight but then with the narrower tire you could loose traction when you need it the most.... introduce yourself in the new member area

When you go to a bigger tire yes your speedo is off and so is the odo. you are traveling more miles and faster than before but using more fuel. engine and drivetrain are moving slower but it takes more hp to get it moving and keep it moving. I'm off by 4 mph (gps) and used to get about 275 Miles per tank. now i get about 230 per tank.

so by going bigger you got better gas mileage... i rest my point... LOL

Whatever size you decide to get make sure it has a very road oriented tread pattern. The more tire noise you can hear = more gas being used.

You guys are forgetting about tire weight. There's a point where the reduced weight yields better MPG's than the reduced diameter burns so they can save on gas, the hard part is finding that sweet spot. I'd go narrower before reducing the diameter and I wouldn't reduce diameter more than 2" below OEM on anything.

The goal here is to reduce WEIGHT, not size. Checkout the different brands and styles too, research the weight of each tire you look at because each tire line is a different weight. 5-lbs can make a huge difference sometimes. Also keep in mind that less weight usually equals less strength unless going for a tire that uses weight reducing materials like Michilin does which are usually more expensive, so make sure to also watch the Max Load Ratings. Avoid Continental ContiTrac, they are lightweight but also a very thin POS tire that won't last like others will.


I'm pretty sure that HyperTech makes a Speedometer/Odometer Calibrator for 2005 and newer Xterras:

http://www.hypertech.com/Products/Inline%20Speedometer%20Calibrator%20Module

so by going bigger you got better gas mileage... i rest my point... LOL

sorry it was a typo. meant to type 230 Miles per tank. its corrected now.

Ok someone do the math for me.

I have large big foot tires and they are loud on the road.
Seems like it takes extra gas just to get them moving.
Just got my X it says i have 112k miles on it.

If i am off by 4 mph on my od then what are the real miles on my car.

Last owner said he changed the tires to the same ones that were on it when he got it the big tires.

So lets say the original owner put the larger tires on it at 10k miles and it's at 112k miles now.
With the 4 mph difference what is the real mileage on my car is it over 150k miles? or what.

This would make my engine and parts all older then it show's right?

actually with bigger tires the milage is less that what it shows..... you keep on saying big foot tires but you never say what size they are or what brand they are....

Big foot are Big-O tires. They are heavy Mud tires if I remember right and the weight of them can kill MPG's. If you're 4-mph off then you're coming out ahead. You've traveled over 150k miles but your drivetrain only has 112k on it. Barrowing a portable GPS is the best way I've found to see how much my speedo is wrong by.

You are not going to be off by 4 mph all the time. It is relevant. You need to find the diameter of the new tire vs. the diameter that was originally on your X and go from there. When your ODO says you are going 4 MPH, you are not going 8 but when it says that you are going 60 , you might actually be going 64 etc.

James, you have an excellent point!!! The MPH have nothing to do with the distance traveled. One rotation of a 33 tire will travel a certain distance further than a 31 tire per rotation. So, there is a specific number of fewer rotations the 33 will need per mile than the 31 and that has absolutely nothing to do with the Miles per HOUR on the Speedo. So, knowing the tire size is critical to caculating the ODO miles correctly and calculating from the MPH on the Speedo would be worse than blind guessing.

its a %
if your tire is 3% bigger than stock your speedo will read 3% slower than your true speed

I'm sure putting a 195/75R16 on the X instead of 265/75R16 or larger would help its overall highway mpg however it'd probably be pretty squirrely on the highway and not so good off road due to the skinnier footprint.