Is bigger really better... ?

[jdkilroy]

Talking about tires here and specifically, tread width. Started thinking about it on the way into work this morning in the middle of a Nor'easter.

I recently changed wheels and tires: 265/65/17 to 265/75/16. my goal was to increase the aspect ratio but I intentionally stuck with the original tread width. My thinking was that by increasing the contact area of the tire, I am deceasing the contact pressure (per unit of area) and that could actually decrease my traction except in situations where I needed to "float" on the terrain (deep sand). I don't think having more contact area would have been helpful today and likely would have reduced my traction considerably.

Are there any guidelines here; the perfect balance between contact area and contact pressure ?

Thanks, Jon

 

[KidVermicious]

No such thing as an ideal tire - as you noted, there's a compromise between hard traction and float, and you can get a tire that does one of those things good, or both of those things not-as-good.

As you noted, floating is good on sand, deep mud, deep snow. Get going too fast though, and "float" becomes "hydroplaning".

 

[emelianenkov]

I got Bridgestone Duelers (I think) 265/65/R17 and they're great for road driving, but once it starts snowing, they pack with snow and make me slide all over the place. I also hydroplane at ridiculously reasonable speeds in the rain! My stock Dunlops didn't do that. It makes me less confident in the abilities of my truck, whether they be intentional scenarios or weather/avoidance procedures.

That's my two cents. Tread pattern has a lot to do with handling too.

 

[BOSMECH]

Stick with the 16's for the New England Snow.

 

[JB.]

Talking about tires here and specifically, tread width. Started thinking about it on the way into work this morning in the middle of a Nor'easter.

I recently changed wheels and tires: 265/65/17 to 265/75/16. my goal was to increase the aspect ratio but I intentionally stuck with the original tread width. My thinking was that by increasing the contact area of the tire, I am deceasing the contact pressure (per unit of area) and that could actually decrease my traction except in situations where I needed to "float" on the terrain (deep sand). I don't think having more contact area would have been helpful today and likely would have reduced my traction considerably.

Are there any guidelines here; the perfect balance between contact area and contact pressure ?

Thanks, Jon

On hard surfaces the results will be mixed but the effects too small to worry about anyway. If psi didn't change, it seems to me, if anything, the new tire would have slightly less contact area due to less deflection from higher air chamber volume. The most noticeable thing on pavement should simply be the small effect the smaller wheel will have on steering and handling. Off-road there should be a benefit and this is a swap I wouldn't mind making myself if I could score some cheap wheels in good condition.

I'd also have to investigate tire availability and pricing before making that move. Have you and, if so, what did you find?

 

[jdkilroy]

I don't think anyone but "Kid" read the original post:

I already made the switch to the new wheel and tire size. The question was regarding contact area vs contact pressure as it relates to traction. So the issue is about different tread widths not wheel diameters or tire side wall height. I did not change my tread width: (265 ---> 265).

Some of the most famous 4 wheeling vehicles out there never had wide tires and I was wondering if there are any figures or guidelines that refer to optimal contact area vs contact pressure. I know there are countless variables but there must be a reasoning behind selecting the best compromise to optimize traction for a variety of off road conditions.

Jon

 

[MikeInNH]

Bigger (actually WIDER) is WORSE in snow. You want the skinniest tire you can that doesn't decrease performance.

With snow you want to dig down to the hard packed snow or the road for good traction. Skinnier tires give your vehicle a smaller foot-print and this more weight per square inch. This helps the tires get deep to where the traction is.

 

[ARK_SWAMP_RIDER]

Here's a great article on this topic, well worth the read IMO. A lot of great details, and also a recommended size for optimum performance.
Expeditions West: Tire Selection for Expedition Travel

 

[JB.]

I don't think anyone but "Kid" read the original post:

I think your post was as clear as the thread title was informative and the sub-forum placement logical.

 

[settytb]

I went skinnier to 255's 75/17's and they are incredible in snow... I've wheeled them and they've gone great. Haven't tried deep mud yet but most normal mud they are way better than my old 275 street tires (not much could be worse as they were pretty bald). So I love mine.

 

[Benski]

Thank's A.S.W. for posting that link about tires from Expeditions West. It was very informative and I learned a lot. It really changed the way I will think about tires now.

 

[teampwr2]

I don't think anyone but "Kid" read the original post:

I already made the switch to the new wheel and tire size. The question was regarding contact area vs contact pressure as it relates to traction. So the issue is about different tread widths not wheel diameters or tire side wall height. I did not change my tread width: (265 ---> 265).

Some of the most famous 4 wheeling vehicles out there never had wide tires and I was wondering if there are any figures or guidelines that refer to optimal contact area vs contact pressure. I know there are countless variables but there must be a reasoning behind selecting the best compromise to optimize traction for a variety of off road conditions.

Jon

The Car MFg . Spend Millions in testing and development Trying to do Exactly what you ask . All the testing for stability and devloping the skid control and anti lock brakes as well as off road perfomance.
I know what your asking and I have found for me the 255/ 265 Width is optimal FOR ME. I Get more "pressure on the ground "using
255/85/16 BFg Mud Km2 I get A Little less but way better milage with bfg at 265/75/16 The atrac Is still responsive in those sizes alot less rotating mass than 285 .. But that is what I have found for what I do..I haave a lift and bumpers winch plus carry alot a crap ! all the time this 255/85/16 bfg km2