[greatwhite]

What are ideal tire size for my '07 LE Crew? I think I'm currently running 265x65x17. I was biking over the weekend and saw another LE with what seem like "fatter" tires. I'm not talking about big off roading tires. I should have stop and look but didn't want to be seen as car prowling. I'm wondering if I should get something with a little more cushion, so something like 265x70x17. No offroading for me, but I do tow a boat in sumer, drive in snow up to the mountains for snowboarding.

 

[dubie2003]

The first number is the width of the tire in mm.
The second number is the ratio of width to sidewall height.
The last number is the diameter of the rim being used.

Since we have that out of the way we can then look at the "fatter" comment. I assume you were saying that it looked wider then your 265s which may be true. You can probably go 275 or 285 and possibly up to 295 but then you run into tire diameter issues since you need to keep the sidewall ratio down to keep the overall diameter to 32".

I think if you went from a 65 series to a 70, you would have more cushion but no the "fatter" look that you saw on the other truck.

 

[greatwhite]

The first number is the width of the tire in mm.
The second number is the ratio of width to sidewall height.
The last number is the diameter of the rim being used.

Since we have that out of the way we can then look at the "fatter" comment. I assume you were saying that it looked wider then your 265s which may be true. You can probably go 275 or 285 and possibly up to 295 but then you run into tire diameter issues since you need to keep the sidewall ratio down to keep the overall diameter to 32".

I think if you went from a 65 series to a 70, you would have more cushion but no the "fatter" look that you saw on the other truck.

More cushion softer ride is what I want. This is what I saw, not the wider description. Bad analogy. Can someone comment on pros vs cons of different tire sizes? Do you lose gas mileage or something? Something's got to give. There's no free lunch.

 

[Clint]

a bigger contact area on the ground decreases gas milege due to more friction.

Clint

 

[Guns90]

Hi dubie. To answer your thread title, the 'ideal size' of tire for your truck is the size that the engineers worked up and put on it at factory. Its the best design to handle the speed range, weight, and load range of the truck in most situations. That being said....

Wider tires will in fact lessen your fuel economy simply because there is more tire (and friction) on the road. Changing the 'aspect ratio' to your tire width will have a very small effect on your fuel economy, but most drastically changes the accuracy of your speedometer. A lower profile tire (smaller aspect ratio number) is smaller in circumference so you will actually be going slower than what your speedometer says. The opposite is true for a higher profile tire.

You can do what you want, but my advice is simply to buy quality tires in the size that the manufacturer has said is best. Hope this helps.

 

[dubie2003]

If you want the taller look, then go from the 65 to a 70 or 75 but in all reality, it won't change it that much. Yes, your mpg will change but not by much.

Now for the statement that the Engineers said to use xyz so that is what I use doesn't hold true to tires/rims as it does for oil/fluids. Why did they put a 75 series on the Nismo/Pro and a 70 series on the SEs? There is no difference in trans or diff ratios on some of the Nismo/SE trims so why the change in tire size?

 

[domoMKIV]

The 265/70-17 is the equivalent to what size comes on the Nismo (265/75-16). Jumping to the 70 series is about an inch taller and imo, definitely looks better (Judging by your post, you agree as well). When shopping for tires, pay attention to the weight of the tire. That is where most of the MPG hit comes from. You can probably look up your current tire and find out the weight, then compare it to whatever else you want.
I did the same thing.
My Grabber AW in 265/65-17 are 36lbs a piece. I compared the following in a 265/70-17 (in P metric, not LT)
Hankook Dynapro AT - 39lbs (Thanks DiscountTire!)
Kumho Road Venture KL78 - 39lbs
General Grabber AT2 - 46lbs
Then I looked into a few P285/70-17 and saw that the Firestone Destination AT was 44lbs. I didn't want to pass up moving to a 33" tire when they weigh less than the AT2's I was wanting to purchase.
Anyway, I just typed this up so you can see that there are some tires close to the same weight when you move to the 265/70-17.

 

[weymouthba]

Will a 70 or 75 tire throw off the speedo?

 

[domoMKIV]

I have read a few people state that the speedometer is calibrated to the nismo tire size (265/75-16 = 265/70-17). Which means the 265/65-17 is throwing off readings already, the speed readout on my GPS tends to agree.

 

[Mylt1]

im running 265-70-17's and they do fill out the wheel well better. at 62mph my speedo is dead on(gps and radar confirmed) above that it is off a little. i believe 65 was actually 67 not sure about slower speeds. if the radar trailer is setup tomorrow i will check 35mph to see how much it is off.

 

[bigdog]

Will a 70 or 75 tire throw off the speedo?

that number alone does not say anything about the tire size, since as dubie already pointed out this value is a percentage. So you can go from a 65 to a 70 and have the same diameter tire by changing the width. So as long as you go from one 31" tire to another then there will be no impact on the speedo.

I have read a few people state that the speedometer is calibrated to the nismo tire size (265/75-16 = 265/70-17). Which means the 265/65-17 is throwing off readings already, the speed readout on my GPS tends to agree.

well just keep in mind that there are differant axles, gear ratios and speed sensors that will all affect the speedo.

 

[weymouthba]

So in other words I would have to go to a 245/70r17 to keep the same ratio, correct? by doing this I would increase my height but have a thinner overall tire. A 255 tire would mean the speedo would be off by about 1.6%. I used the calculator located here:

Tire Size Calculator - tire & wheel plus sizing

 

[ffips]

The first number is the width of the tire in mm.
The second number is the ratio of width to sidewall height.
The last number is the diameter of the rim being used.

Restating the above + a little: Using P265/75/R16 and LT265/75/16
P or LT is whether the tire is "pmetric" or "light truck" (light truck as in 1/2 ton or > light truck)

First number = width in milimeters = 265 milimeters

Second number = sidewall height as a % of the width = 75% of 265 or 198.75milimeters

Last number = rim size in inches= 16" wheel

I have no clue why it was decided to mix metric and standard (milimeters and inches).

So in other words I would have to go to a 245/70r17 to keep the same ratio, correct? by doing this I would increase my height but have a thinner overall tire. A 255 tire would mean the speedo would be off by about 1.6%. I used the calculator located here:

Tire Size Calculator - tire & wheel plus sizing

Here is a tire size calculator that might help you with this: Tire size calculator This one provides more of a visual of what is going on. Can view from side of vehicle or in front of/behind vehicle.

Using the stock Nismo size of 265/75/R16 and then changing to a 245/70/R17 you will have the following happen:

stock specs: Nismo @ P265/75R16
7.8" sidewall
15.8" radius
31.6" diameter
99.4" circumference
637.0 revs/mile

new tire spec: P245/70/R17
6.8" sidewall
15.3" radius
30.5" diameter
95.8" circumference
66.1 revs/mile

Speedometer reading with non stock tires is 3.6% too fast meaning that when the speedometer reads 60, you are traveling 57.8mph.

Keep in mind I went with stock Nismo vs your new tire size. If you have 17" wheels already then my numbers are slightly different.

You will also be changing your contact patch on the ground by (removing) 20 milimeters.

 

[weymouthba]

I'm not really looking at the Nismo / PRO4X tire size as a guide, I just want something taller that doesn't throw off my speedo. With a 255/70r17 the speedo would only be off by 1.6% which is something I would be able to live with.

Second question: is there really a difference between a passenger tire and light truck tire?

 

[ffips]

I'm not really looking at the Nismo / PRO4X tire size as a guide, I just want something taller that doesn't throw off my speedo. With a 255/70r17 the speedo would only be off by 1.6% which is something I would be able to live with.

It would be easier to assist if you shared the current tire size that you have and if your speedometer is correct or not. I used the Nismo/Pro4X size because:

• I know it off the top of my head as I have one.
• Many say that size (265/75R16) actually makes the speedometer correct.
• Nissan uses at least three different stock sizes.

You have referenced a 17" wheel which tends to suggest a LE? I don't know what size comes stock on a LE.

Second question: is there really a difference between a passenger tire and light truck tire?

Yes there are a lot of differences between Pmetric and LT tires.

• Pmetric tend to be properly inflated at 35psi whereas LT tires are not.
• LT tires tend to be properly inflated at 45 psi or higher.
• LT tires tend to have more plys than the Pmetric -- 6 or more vs. 4
• Some feel the LT tires offer a higher load range. This is NOT always true, be sure to check what you buy. If you chose to run a LT tire underinflated for a "softer" ride you will also be lowering load capacity. An underinflated LT tire may or may not develop sidewall issues.
• Pmetric tires tend to offer a more comfortable ride over the LT tires.
• Pmetric tires should be lighter than LT tires since they have fewer plys
• Chances are unless you regularly off road and fear punctures or regularly tow near the capacity of the frontier, a Pmetric tire will satisfy one's needs.

There are probably more, this just comes readily off the top of my head.

 

[weymouthba]

I have the stock LE 265/65r17. From your description I think that LT tires will work fine.

 

[bigdog]

I'm not really looking at the Nismo / PRO4X tire size as a guide, I just want something taller that doesn't throw off my speedo. With a 255/70r17 the speedo would only be off by 1.6% which is something I would be able to live with.

Not sure how else to say this, but the thing that throws off the speedo is the height of the tire, so if you go to a taller tire you will impact the speedo.

The width of the tire may affect your mpg but it will not be visible to the speedo. and the best way to determine if one tire is taller then another is to look at the diameter measurement.

 

[domoMKIV]

I have the stock LE 265/65r17. From your description I think that LT tires will work fine.

Keep in mind that an LT tire is going to weigh quite a bit more than a P tire which will have more of an impact on your MPG and acceleration.