17" tire recommendations
 

The "Summit" tires that came on my X are old and cracking. I can't even find date codes on them (and have never heard of this brand before). Looking at Cooper Discoverer Road+Trail AT or Discoverer AT3 4S in the stock 235/65x17 size.

The old tires are 245/70x17, but there is no detectable speedometer error via the GPS in my dash cam and the local scolding signs that freak out if I'm going over the limit, which is weird because these tires are taller than stock with a longer circumference.

I know others here have gone quite a bit wider/taller on the stock 17" rims, other than maybe a softer ride and lower fuel economy (it's bad enough already, thanks) what's the benefit?

my tire choices from the past 20 years are mostly...
 

I did a search, and found that "Summit" tires are an offshoot of Yokohama tires (Summit is a product of the Alliance Tire Group, which was acquired by Yokohama Tire, in 2016). Their focus was to make mostly off-road, industrial, and agricultural tires, but also make on-road tires as well.

While speaking re: Yokohama Tire(s), I currently have a set of nearly new YK-HTX All-Seasons (in 235/65r17) tires on my X5, with so little miles on them that the little "tire whiskers" are still extant. A good-to-great tire, IMO, but I like Yokohama tires a lot (I have had Yokos on my '09 HHR Panel...still good, after 65000 miles..., and on our '92 Olds Achieva SC Quad-4...now gone...). If I had bought the X5's tires myself (they were newly-installed just prior to my geeting it), I would've opted for Geolandar All-Terrains (my overlanding goal hasn't been met, yet). So, for how I've been using the X5, the AS tires are good enough.

I also like Cooper tires, and have used them on several vehicles, too. They are presently on my '04 Chevy 2500HD (245/75r17 Discoverer-RTX All-Terrains) w/low miles, and '98 GMC 1500 (275/60r15 Mastercraft Avenger G/T, a less-expensive Cooper tire) brand-spanking new, and I've had other Coopers on other trucks & cars alike.

You can't go wrong with a Yokohama or Cooper tire, as far as I'm concerned. And throw in General Grabber AT tires, if you choose to go all-terrain (I have General Grabber AT 2 - 27X8.50R14's on my home-built squareback trailer). As far as sticking with 17" wheels, I'm old-school, and like the extra sidewall they provide.

Thanks, I was also considering Yokos as I had two sets of Avids on my Volvo 240 (RIP, Mrs Klankenborg). The first set dry-rotted after years of sun exposure, to the point that I could see steel cords through the cracks. Still plenty of tread left but they had to be replaced. The Yoko Geolandar A/T G015 also looks like a good choice.

I haven't bought new tires in years and am kind of shocked at how expensive they are now for anything that's not Chinese junk.

Bmw codes the speedo to run 3mph fast. You will find that out of you go down to smaller tires :-)

I found the stock 17s a very comfortable ride on wife's e53. Way way to soft for my driving. But fantastic grip in snow with snow rated tires!

My X5 has 255/60R17 Nexen Roadian HP SUV tires. I like the wider stance. It's a great tire for my area. Good traction and quiet ride. 10k plus miles and no issues.

Hmmm, yes those do fill out the wheel wells nicely. /60R27 should be close to OE aspect.

Interesting that they did that so long ago. My F30 was coded such and I turned it off, but going from OE tires to wider/shorter seemed to increase the speedo about 4mph fast. Hope that's not altering the odometer!

265/55R17 also fit.

265/65R17 is ~2% taller. It would put you half way to coded speed.
https://tiresize.com/calculator/

255/60/17 or 275/55/17 were my choices.

The odometer and internal speed are correct with factory tires. When you changed to faster speedo you changed to faster odometer also.

4/70=0.057 almost 6% if the 4 is at 70. Unlike factory where three offset is not a ratio, if you're fast 4 mog that is at a specific speed say 70 mph

You can tell the speedo is different from internal by reset the average speed while on cruise I think the avg uses actual speed.

15000*.057=855 the odometer will be adding 855 miles per 15000 at that ratio.

I think the digital speed can be coded to show the right/wrong speed but when I tried on my e70 and F10 I don't remember it working. I don't recall a setting to code the dial speedometer to be correct on either e70 or f10

On our e53 I remember the avg speed being 3mph lower than speedometer.

Oh wow that's a very useful site. Thanks!