I know there is a 1.7 inch difference in the tires. But I'm wondering if it is worth worrying about. The 265's are 31.7 inches and the 275's are 30 inches. The 275's are about half an inch wider.

I'm thinking more of looks. I have a 2001 Sport model. Do you think the lower profile/wider 275's will look better?

 

Hello deep6blue,

Is your truck a 2x4 or 4x4?

 

I've got an '01 SCab Sport 5.4/3.55 2wd with the 275/60/17 BFG.

For a 2wd I would think the 275/60/17 are better for the simple reason you would feel the size difference in performance with the bigger tires to the tune of about 5.6% in overall gear ratio.

That would make a 3.55 gear closer to 3.31 and would also throw off the speedo about 3.3 mph at 60 mph.

I'm looking into whether 275/55/17 will work with my 7.5" wheels when I need tires. They are about 29" tall as I'm wanting a little more gear.

 

rkjerue- 4x2

ChiDiver - Since the 275's are actually smaller in diameter, wouldn't the gear ratio go the other way, to 3:79 from 3:55. Not trying to be picky, I'm just making sure I understand.

Interesting tidbit. The 265's turn 657 rotations per mile, and the 275's turn 694 rotations per mile. So the 265's should get better mileage on the highway. But the 275's would offer better pickup, I think.

So anyway, back to the looks. I've just seen some trucks with some really dinky tires, they just don't look right.

 

As far as looks I like the wider 275/60/17(30") but my truck has a 2" rear drop that decreases the wheel well. In my opinion the wider ones look better, but that's just that, my opinion. Your's is the one that ultimately matters the most.

Whenever you go to a nonstock tire size there is going to be a speedo difference. A true 60 mph will indicate ~ 3.5 mph off if you go from one of those tire sizes to the other.

If you go to the larger diameter from the smaller then your speedo will read ~56.5 mph at a true 60 mph.

If you go to the smaller diameter from the larger then your speedo will read ~ 63.5 mph at a true 60 mph.

 

Thanks much ChiDiver

 

I have 275/65-17 on my 2002 sport and like the look. A little wider and a little shorter than 265-70. I felt no performance change but did have to adjust my speedo a little. It was about 2 mph off.

 

brianxtreme - very nice truck. How did you have the speedo changed? Did you do it yourself or did the dealership do it?

 

deep6blue

I have the Superchips Micro tuner wich ables you to adjust for tire size changes and gear ratio changes.

 

Rule of thumb: smaller diameter tires=feels like lower gears
Larger diameter tires=feels like taller gears.
As soon as you put larger diameter tires on your truck, your first impression will be lack of power because you were used to the smaller tires. When I had my Dodge Ram, I went from 245's to 265's and there was a big difference in the perceived feel of power.
As a side note: I had someone tell me one time that the computer can be reprogrammed for the new tire size so the speedometer reads correctly. I don't know if that is true, but it would sure make things a bit easier. Years ago, all we had to do is replace the little gear at the end of the speedo cable where it attached to the drivetrain with a different ratio gear so the speedometer would read correctly. That's a heck of a lot cheaper than swapping out the ring and pinion just because you bought tires one size larger. THAT really has never made any sense to me at all. Sheesh, change something else or just leave it.

 

i have 265/70's on mine, and my speedometer is off 7%, when its says im going 60, im really goin 64.2. theyre great and they dont rub. theyre on my 97 f150 stx 2wd w/4.2

 

Deep6blue,

I did this exact switch to my 99 Sport and lost a good 2mpg as a result! I tto thought the increased tire height would equate to a higher rear gear, and thus improve my mileage on the highway. It didn't! I would stick with the 275/60-17's if I were you, or go to the 275/65/17's, which is what I should have done. Unfortunately, the tires I wanted (Bridgestone Revos) only came in 265/70-17, and the loss of power was also noticable. Switching to a 3.73 gear would probably counter the change in tire height, but that's another added expense! I just hope the choices is better amoung the 275/60-17 tires when it comes time to purchase my next set!