Switching from 20x9 to 18x8.5 wheels. Which of these 2 tire sizes?

BigRedd · December 2, 2015

I have a 2015 Sierra AT CCSB with stock 20x9 wheels and 275/55R20 tires. I'm going to get a set of 18" OEM wheels and snow tires for winter. The OEM 18s are all 8.5" wide. The stock tires on the stock OEM 18x8.5" wheels are 265/65R18.

I have my heart set on Nokian Hakkapeliitta R2 SUV snow tires which, as Murphy's Law would have it, do not come in 265/65R18. [Available sizes here: https://www.nokiantyres.com/winter-tyres/nokian-hakkapeliitta-r2-suv/]

According to tiresize.com, the two sizes that Nokian DOES have which are closest in diameter to my stock 275/55R20s are:

(1) 275/65R18 (+0.6% diameter according to TireSize); or

(2) 255/65R18 (-2.5% diameter according to TireSize).

I'm leaning to the 255/65R18s because narrower tires are better in snow, but I'm concerned about the 2.5% drop in diameter/circumference. On the other hand, I'm concerned that 275s are too wide (10.8") for 8.5" wheels. But from a looks perspective I like the fact that I wouldn't lose any diameter.

Which would you get (and why, if you'd be so kind)? Any clear dealbreakers either way?

Thanks.

fondupot · December 2, 2015

I have a 2015 Sierra AT CCSB with stock 20x9 wheels and 275/55R20 tires. I'm going to get a set of 18" OEM wheels and snow tires for winter. The OEM 18s are all 8.5" wide. The stock tires on the stock OEM 18x8.5" wheels are 265/65R18.

I have my heart set on Nokian Hakkapeliitta R2 SUV snow tires which, as Murphy's Law would have it, do not come in 265/65R18. [Available sizes here: https://www.nokiantyres.com/winter-tyres/nokian-hakkapeliitta-r2-suv/]

According to tiresize.com, the two sizes that Nokian DOES have which are closest in diameter to my stock 275/55R20s are:

(1) 275/65R18 (+0.6% diameter according to TireSize); or

(2) 255/65R18 (-2.5% diameter according to TireSize).

I'm leaning to the 255/65R18s because narrower tires are better in snow, but I'm concerned about the 2.5% drop in diameter/circumference. On the other hand, I'm concerned that 275s are too wide (10.8") for 8.5" wheels. But from a looks perspective I like the fact that I wouldn't lose any diameter.

Which would you get (and why, if you'd be so kind)? Any clear dealbreakers either way?

Thanks.

275's are fine on 8.5" wheels. I used to run 285's on my old 2002 Silverado 16x6.5 wheels.

That said, 255s will be better in the snow. And the smaller diameter shouldn't be much of an issue. You'll just be going slower than what your speedo says. Not by much. At 60mph on your speedo you will actually be going 58.5.

But if it was me, i would stay closer to the stock size for aesthetics more than anything. 255's might look a little too dinky on that truck.

BigRedd · December 3, 2015

Thanks, fondupot. I found the Nokian US Product Guide and the 275s are recommended for 7.5 - 9.5" width rims. So the 8.5" wide OEM 18s are right in the sweet spot. It's simply a question of looks vs. snow performance at this point. Where I'm leaning now is that the whole reason I'm willing to drop $1,700 on winter rims/tires is for snow performance. If it were about looks, I'd keep the stock 20" AT wheels, which I love (with the crappy Goodyear SRAs, which I don't - they were sliding all over the place going up a hill under throttle today in light rain).

So while I agree with you that the 275s will look better, I may nevertheless go with the 255s. I'll wait until late tomorrow to call the ball, so if anybody else wants to weigh in, I'm all ears.