What size tires?

[CJ_4]

I've got a '97 K1500 that I leveled the front end up by tightening the torsion bars. I was wondering what size tires any of you might have. I have 245/75 R16, but I want something a little taller and a little wider to fill in the fender gap. I was thinking about 275/60.

[DmaxMaverick]

The 275/60/16 would be fine. As would a 265/75/16 (most popular). A tire as large as 285/75/16 can be fitted, but minor fender adjustments may be necessary.

[CJ_4]

thanx Dmax. I definitely don't want to do any fender modifications, so I don't think I'll get the 285/75. I'll do some shopping around to see what type tire I want but I didn't know how big was too big.

[DmaxMaverick]

Just as important as the tires you choose, are the wheels. Width and backspace is critical to fender clearance. Too little backspace and the wheels stick out too far, and will still contact the fender(s). Not an issue if you are using a stock size wheel. If you go aftermarket, you'll need a backspace of 4-1/2" (minimum) or 4-5/8" for an 8" wheel. Other sizes can be calculated using that as a reference.

[JFerg65]

I'm always glad to see there are others out there already asking the same questions I have. What are peoples thoughts on putting the newer 17" 8 lug rims on. Oh yeah, It would be for my 96 2500 Suburban.

I know it will mess with the speedo. But it would also help with my 4:10 gears a bit wouldn't it? I know there have been many posts regarding this, but it always seems to get a little blurry by the end

[DmaxMaverick]

I'm always glad to see there are others out there already asking the same questions I have. What are peoples thoughts on putting the newer 17" 8 lug rims on. Oh yeah, It would be for my 96 2500 Suburban.

I know it will mess with the speedo. But it would also help with my 4:10 gears a bit wouldn't it? I know there have been many posts regarding this, but it always seems to get a little blurry by the end

The wheel size has absolutely nothing to do with it. The tire diameter and wheel backspace (offset) is the key. It doesn't matter, even if the wheels are 22". A 32" dia. tire on a 9" wheel with a 5" backspace is the same, regardless of the wheel. You can mix/match tires and wheels, as long as the tire is where it needs to be, in the end. Tire diameter and width, and wheel backspace is all you need. Ignore the wheel diameter for this.

[JFerg65]

That should shave a few hundred dollars off the future project.

[DmaxMaverick]

And.....

The speedo is only an issue with a tire diameter change. Depending on your current tire size, your 17" wheel replacement may or may not be the same (or close enough). If tire diameter isn't a concern or you don't want larger/smaller tires, buy tires of the same diameter as what you have now. Once again, the wheel size plays no part in this. In any case, if the speedo is no longer accurate, a VSSB hack isn't too involved. More info on that HERE (http://www.thedieselpageforums.com/tdpforum/www.thedieselpage.com/65book.htm), and a search of the 6.5 and tech forums should help.

[JFerg65]

Thanks for the follow up. Now, please correct me if I'm off base here. From all my reading regarding this, it is possible to run a larger time (diameter) and in turn to some degree improve the gearing to get the RPM's down at highway speeds and increase mpg's (given speedo is corrected for such diameter change). At this point it would be the only reason for me to step up tire diameter size. OK, I think I might bite the bullet and get newer style 8 lug Alum rims because I think They look cool!

I hope that made sense.


Thanks

[DmaxMaverick]

Increasing tire diameter may increase MPG slightly. So slightly, in fact, whatever you spend to justify the change, you will never recover (even at today's fuel prices). In most cases, it is the opposite. Larger tires increase the rotating mass and rolling resistance. Wider tires are worse, with increased rolling/wind resistance, and increased rotating mass. Increased rotating mass can also increase unsprung weight, which can have a profound effect on ride quality. In most cases, you will keep the mileage you had, at best. One bonus is, at highway speeds, the engine noise is less. Tire noise, on the other hand, can increase, depending on the tire you select. Many variables when we mess with weight, friction and ratios.

Nowadays, appearance can be a higher priority than mileage, ride quality, or other comforts. All I can suggest is to put function before all else, then weigh what's left for positives/negatives.

[JFerg65]

Well that does it for me, stock is what she'll stay. Thanks for the input. I put the money into something else on the truck, I'm sure that won't too hard.

[CJ_4]

yeah i'm just gonna stick with stock wheels but just get some bigger tires. thanks for all the advice.

[DmaxMaverick]

yeah i'm just gonna stick with stock wheels but just get some bigger tires. thanks for all the advice.

What size did you have in mind? 255/85/16 is a 33" tire, and will have less of a mileage impact than wider tires. It will also fit on stock wheels (6.5" wide). This is the only larger tires size that may offer a mileage gain. 265/75/16 also fit, are about 31.5" tall, but tend to soak mileage a bit more. 285/75/16 will also fit (with minimal modification), but are not recommended for stock width wheels. Some folks do it, but it is not recommended. They will kill the mileage more than the others (11.25" wide tire). I have this size on my 2001, but with 8" wide wheels. There are some images of them in my sig. link.