[FourMoBro]

I am looking for feedback on winter tire width.

I currently have the 20" wheels due to the Touring trim. I am purchasing a set of OEM 18" rims to run a winter snow tire set. The purpose of this set is simply for skiing/mtn pass trips here in the PNW. They will be put on the night before, and taken off when the trip is over, running the 20s the rest of the "winter". I have never had to put on chains, although you are required to have them if you running all-season M+S tires. When traction tires/chains are required, you don't have to put them on if your vehicle is AWD/4WD. The only time you would be required is if there was law enforcement stopping everybody and only permitting chains to pass. Some states may call this a "Class C road closure" if memory serves me right. The problem with chains on the Ascent is that the owner's manual really doesn't want you to run chains, but there is a small section saying Class S traction devices are OK. The stock tire width for both the 20" and 18" is 245. If you were buying snow tires, in this case for an 18" rim, would you go with the stock tire size 245/60R18 or would you go for a 235/65R18 set? I think the narrower tire would provide more clearance for chains on the inside. The downside is that it is a taller tire. There seems to be ample clearance there. Chains are meant for low speeds and there are generally not huge potholes where suspension would bottom out. Price difference is nil between the two. What Would the Forum Do (WWFD)?

Thanks

 

[zegilbert]

I would go narrower with more sidewall (taller and narrower - better to cut through the snow and not float). That's my current plan.

 

[DAC]

Sorry to dodge the question (since I don’t have enough knowledge to answer!), but I’m in the same boat and I’ll even go a step further back and ask what tires you plan on buying? I also plan on 18” wheels instead of 20. Since you plan on changing the wheels the night before, does that mean you’ll be getting studded? I will not be, and am looking for advice on studless winter traction tires.

 

[FourMoBro]

Sorry to dodge the question (since I don’t have enough knowledge to answer!), but I’m in the same boat and I’ll even go a step further back and ask what tires you plan on buying? I also plan on 18” wheels instead of 20. Since you plan on changing the wheels the night before, does that mean you’ll be getting studded? I will not be, and am looking for advice on studless winter traction tires.

The first choice I am considering are the Blizzak DM-V2, which would be purchased from either the local Firestone store, or possibly Costco. The other choice would be the Wintercat SST, which have stud holes should anyone want to stud them later. Those could be purchased from the local Les Schwab which are everywhere in the PNW.

 

[QuadView]

I know this may go in the wrong direction, but I was thinking getting a new set of "inexpensive" rims and put on some capable dirt, snow, winter tires. What would you guys recommend? Wheels? Tires?

 

[crowdc]

@Robert.Mauro has done a BUNCH of legwork on finding rims that fit. I would do a bit of searching on the forum for his work.

 

[Robert.Mauro]

I know this may go in the wrong direction, but I was thinking getting a new set of "inexpensive" rims and put on some capable dirt, snow, winter tires. What would you guys recommend? Wheels? Tires?

@Robert.Mauro has done a BUNCH of legwork on finding rims that fit. I would do a bit of searching on the forum for his work.

So far, 700 miles on and off road on the Liquid Metal Shadow 17x7.5 rims. Loving them.

 

[cjkenton]

Unless your driving on sand, or climbing rocks with your PSI at 10, a narrower tire will always give you more traction. More poundage per square inch. (On sand, you want the weight of the vehicle as spread out as possible)

 

[higherground]

Living in sonw country I’ve always ran blizzaks throughout the winter. Currently thinking of buying a set for my 20” touring wheels and getting a set of 18” for summer so I can have a little more meat for forest roads. Really not liking the 20” wheel and tire combo off road.

 

[Burutoo]

The first choice I am considering are the Blizzak DM-V2, which would be purchased from either the local Firestone store, or possibly Costco. The other choice would be the Wintercat SST, which have stud holes should anyone want to stud them later. Those could be purchased from the local Les Schwab which are everywhere in the PNW.

This is what I'm going with as well; the Blizzak DM-V2. We had the V1 on our outback and they were great. going with a 245/60R18 on 18x8 wheels.

 

[DAC]

going with a 245/60R18 on 18x8 wheels.

What wheels are you getting? And are you on stock 20” wheels and getting the 18’s, or do you already have 18’s?

 

[Burutoo]

What wheels are you getting? And are you on stock 20” wheels and getting the 18’s, or do you already have 18’s?

We do have the factory 20's on the touring model. I'm ordering a set from tirerack with 18" wheels. Found a nice looking fairly inexpensive set by MSW.

 

[zegilbert]

We do have the factory 20's on the touring model. I'm ordering a set from tirerack with 18" wheels. Found a nice looking fairly inexpensive set by MSW.

I have the same setup and have been looking at winter options at Tire Rack. You getting the TPMS monitors?

 

[zulater]

Unless your driving on sand, or climbing rocks with your PSI at 10, a narrower tire will always give you more traction. More poundage per square inch. (On sand, you want the weight of the vehicle as spread out as possible)

This is not true.

Traction (Frictional force) is equal to mu (coefficient of friction defined by the materiel, tires in this case) multiplied by the normal force (weight in this case). Ff = u * N. Width and/or contact patch has nothing to do with it. Wider tires spread out that weight to give you less pounds per square inch as mentioned and could let you traverse sand or mud easier by not sinking in but it does not change mu or the normal force.

 

[zegilbert]

This is not true.

Traction (Frictional force) is equal to mu (coefficient of friction defined by the materiel, tires in this case) multiplied by the normal force (weight in this case). Ff = u * N. Width and/or contact patch has nothing to do with it. Wider tires spread out that weight to give you less pounds per square inch as mentioned and could let you traverse sand or mud easier by not sinking in but it does not change mu or the normal force.

I would add that the coefficient of friction is really referring to two surfaces. In snow and rain, of course the coefficient of friction between the tire and road is greatly reduced when a layer of snow or water (lubricant) is introduced between them. A narrower tire will better displace the lubricant and "slice through" to the road surface more readily, vs. floating like a wide snowshoe. Same potential traction for both the narrower and wider tire (in dry conditions), but the narrower tire will allow more force to be imparted directly to the road, so more effective traction with the narrower (in adverse conditions).

 

[zulater]

I would add that the coefficient of friction is really referring to two surfaces. In snow and rain, of course the coefficient of friction between the tire and road is greatly reduced when a layer of snow or water (lubricant) is introduced between them. A narrower tire will better displace the lubricant and "slice through" to the road surface more readily, vs. floating like a wide snowshoe. Same potential traction for both the narrower and wider tire (in dry conditions), but the narrower tire will allow more force to be imparted directly to the road, so more effective traction with the narrower (in adverse conditions).

For water I'd be surprised if there was a difference unless tread depth (worn tire) is an issue.
Slick snot snow I'd potentially agree but again tread depth could matter.
Packed snow they'll be identical as you aren't reaching the pavement, same with ice.

Realistically we're talking a couple inches difference in width. Not a bicycle tire vs. a 245 tire. Though if you could get 4 spares and Blizzaks to go on them that might be something

 

[Robert.Mauro]

Interestingly, none of what actually happens made much sense to what I thought should. For instance, it's ridiculously easy to get stuck in fine sand with filled tires. Been there, done that. It's ridiculously difficult to get stuck in fine sand with aired down tires. Feels like driving on a bumpy road.

 

[Burutoo]

I have the same setup and have been looking at winter options at Tire Rack. You getting the TPMS monitors?

Yes I will. Even though I think they are stupid I don’t want to see the tpms light lit up for half the year.

 

[zegilbert]

Interestingly, none of what actually happens made much sense to what I thought should. For instance, it's ridiculously easy to get stuck in fine sand with filled tires. Been there, done that. It's ridiculously difficult to get stuck in fine sand with aired down tires. Feels like driving on a bumpy road.

Mo' surface area, mo' traction

 

[zegilbert]

Yes I will. Even though I think they are stupid I don’t want to see the tpms light lit up for half the year.

Might've missed it, but what tires are you going with?