I'm driving a 2007 Xterra offroad up into the Washington mountains each weekend. We're getting up to about 4-5000' and often drive on packed snow/ice. Sometimes were getting freshies.
I'm thinking about going with a slightly narrower tire to increase traction.
The std is 265/75R16 and I'm looking to move to a 255/65R17. I'm getting used 17" rims so I don't have to swap out in the spring.
This takes my width from 10.4" to 10". I think this will improve traction in snow and ice.
The downside is that it will reduce the circumference from 99.4" to 94.4". This means the speed will read 63 when I'm doing 60. Not a big deal if it keeps me out of the ditch.

I'm hoping for some feedback on making this change and if there will be any unexpected downsides.

Thanks,
Chuck

Over 5% difference in diameter, is a fair amount.

255 is still too wide if you really want true performance under the conditions you described. For a winter tire it's a good idea to increase profile when you can. By flexing sideways the high profile helps prevent slipping when bouncing in a turn. Look at winter rally racing. (The rule is different on pavement though...)

245/75-17 would be a better choice. Bridgestone makes it. The diameter is nearly identical to the std 265/75-16, the tire is narrower and higher profile; the contact patch is longer. That would be a true winner.

Marc

Thanks Marc. That makes sense. I was looking further and think I could go with another 16" rim and a 245/75R16 tire. The Nokian Hakkapeliitta LT (without stds)looks like a pretty nice tire.
That makes the diameter difference only 3.7 which seems more reasonable.

Just curious if there's been anyone who's run a 235/85-16. I just bought an Off Road and will be hitting the snow with it. The diameter ends up being very close to the stock 265/75-16. I'm just worried what it will be like on pavement; squirrely, increased braking distance, etc. Please let me know your experience or thoughts. Thanks.

In the late 70s we ran 7.50-16 or 7.50-16.5, (about 32") on wheels 6" wide or less, on the Suburbans and pick-ups in James Bay. We drove these vehicles at 80 mph+ on snow and ice easily. However, the tires were prone to unseat from the rim if we attempted slides, this pay tribute to the grip they had. I believe it could not be impressive on pavement, although I only drove them on gravel during the summer.

The 235/85-16 you mention measures 9.3" wide, is a 32" and would be mounted on a 7" rim. That's 2" more than what I mention, on a wider wheel. This would make an awesome snow tire. If I had 16" wheels this is what I'd mount.

I don't think this would make the vehicle too squirrely. It might increase brake distance on pavement. That's the trade-off for a no-compromise snow tire. Drive accordingly.

Rubber is just like gasoline, consumeable. I'm glad it is that way, so we can experiment. Tire retailer will probably recommend against it, I'm used to that myself.

For the winter I mounted Grandtrek SJ6 30x9.50-15 on my 15" steel wheels. (equivalent to 241/78R15, not too far from 235) Every retailer recommended not to, yet this is the same diameter as OEM 265/70R15. These tires have twice the grip that my BFG AT had on snow, ice and wet pavement. I have plain fun when road condition is bad.

Marc