hector200sx

get that ITR in the garage

cackalak han

Oh, trust me, it did live in the garage. But when it came out to play, it came out to PLAY! I took care of the thing, but I didn't baby it, either. Too bad I sold her. Many good memories of her on the track.

Rallyroo

Too wide for snow? Tell that to the World Rally Championship folks on the snow stages.

MadCityRich

Yes, there couldn't be any difference between WRC and street driving. What was I thinking?

MadCityRich

cackalak han

235's ain't anywhere near too skinny. I still get great traction in the snow and in the dry. 235/85/16's. A lot of LR's use this size, as well as Austrailian outback guys.

And a lot of racing technology is trickled down to street driving. I'm not saying all applies, but you can't dismiss everything due to it being on Rally Cars.

MadCityRich

Surely there must be a limit to the benefits of skinny tires. I don't have experience with 235's, but at 9.5 inches, it's not that radically different from 265's. But what would happen as we go down to 225, 215, 195, etc., etc.

My main concern is that there's a lot of forces at work on a tire that could cause lateral traction problems. With a skinnier tire, the contact patch is longer and narrower than with a wider tire. So if we have a looser suspension, we get more lateral forces in a turn. For example, a sway bar shifts forces to the inside suspension in a turn. Take the sway bar away and the forces are greater on the outside of the turn. Couple that with less lateral traction and we may be more likely to skid in a turn. We have high center of gravity vehicles without the tightest of suspensions.

If I'm going forward or backward and not worried about turning, then I agree that all else held equal a skinnier tire is more useful. However, if I'm driving forward and hit a slick patch, I have a greater chance of having some traction with a wider tire due to the patchyness of the road surface. If it's all snow covered and slick, then it doesn't matter. Skinny is also better for cutting through snow.

But it's a compromise when we encounter real world driving conditions. WRC cars are optimized with suspension tuning and tires being designed for the type of course and surface. We don't have that luxury, but it's not to say we don't benefit from their experience and learning. We just don't drive in a WRC world.

MadCityRich

okie81

As stated above numerous times I must agree, its all about the tires, but they can't make a crappy driver any better in the snow.

4rx

I used to have the firestone destination mt 235/75/16. they kicked ass in the snow when aired down!

Meterpig

A narrower tire will allow more lbs of pressure per square inch and allow you to dig down a bit more. Bigger tires are going to allow you to "float" on top of the snow in theory.

A 9.5 inch tire was specified on many 4runners from the factory.

MadCityRich

This is a common misconception. For tires of the same diameter and the same air pressure, the contact patches are the same area, with the same force per unit area. The difference is only the shape of the contact area. Once we get into major deflation, this can change, but with normal tire pressures, this is the case.

The question comes when we talk about the type and reason for the traction. In that case, it's the shape of the contact patch that matters, but more in the nature of the tire design than anything else (tread, materials, siping, etc.).

MadCityRich

muddpigg

iTrader: (1)

Hell yeah they do, I've had them down to 5lbs. They're heavy sidewall make thing other radials can't tolerate happen. 33/12.5/15

Joshs98Runner

I have never had much confidence in my 4Runner when it gets kinda icy. When I bought my runner it had some stock size Bridgestone Dueler H/T's or A/T's...those tires made it feel like I was trying to drive a saucer sled in the snow. People say good things about the Revo's but the rest of the Bridgestone line is junk IMHO. I have the 265/75 BFG A/T's now and am pretty happy. It does very well when there is at least a couple inches on the ground or somewhat compacted snow that hasn't frozen yet.

All in all I think the 4Runner does well in the winter but unless you are in deeper than 6" of snow my friends Subaru wagons are more predictable with all seasons...

Matt16

Not if the laws of physics say anything about it. lets take a 33x9.5 and a 33x12.5. If your contact patch is 6" long x 9.5" wide, thats less area of a tire with a contact patch of 6" x12.5". Each tire still supports the same amount of weight, but each square inch of contact patch carries less weight with the wider tire.

cackalak han

Tires, tires, tires! Why not do a lap around Laguna Seca in a GT3 RS with cheap, bald tires and tell us how much the GT3 sucks compared to a Civic riding on S03's?

MadCityRich

You are assuming that the contact patch is determined by the width of the tire. In fact, contact patch is determined primarily by air pressure in the tire and the load on the tire (the vehicle weight). A wider tire, with the same vertical force and air pressure, will have a wider patch laterally and shorter patch longitudinally than a tire that is narrower, but of the same diameter.

Simply running a wider tire does not increase your contact patch. For a given vehicle, with the same tire diameters, and air pressures, the contact patch area will be the same regardless of tire width. Only the shape of the contact patch changes. This can change the optimization of friction forces, but that's about it. There are other factors that can cause variance on this, such as sidewall stiffness, but this impacts things at the margin.

Your situation, above, that has a 6" long x 9.5" contact patch and a 6"x12.5" contact patch, would require that the 6x12.5" tire be of a larger diameter, or operating with significantly less air pressure, or on a heavier vehicle. For a given vehicle and the same tire diameters and tire air pressures, you cannot have the situation you described. Tire diameter isn't even that much of a factor. It's mostly the air pressure and vehicle weight that causes the tire to deform to create a contact patch.

MadCityRich

Adventureh

My 4-Runner has slid off the road twice. The first time, I thought it might be the tires. With the BEST Goodyear tires, it slid off road again. I was not stopping or accelerating or turning! Any slight dip in the road will send it sliding sideways with no control. I luckily hit an embankment both times instead of sliding off down a steep incline. The 4-Runner just cannot handle an inch of snow. I have had other 4x4 vehicles and have never had a problem, except with the 4-Runner. In fact, I have driven rear wheel drive cars in the snow with much better control than in the 4-Runner. It is embarrassing to be looking at the damage to my 4-Runner while a couple in a Buick passes by with ease.

turbo8

Thanks for the a thread revival, sounds like something else is wrong with your 4runner. Maybe start a new thread describing your problem.

billabob1234

I had a moment a few years ago where I nearly slid off the road in my 4runner. I was getting a little overconfident because it was doing pretty well in the snow. Then I got to a downhill section with a turn at the bottom, got going to fast, and the car didn't turn right away when I went to turn. Thankfully I recovered and didn't go off the road. Moral of the story is don't get overconfident, and take it slow. Also, I had decent tires, Falken Ziex.

wyoming9

iTrader: (1)

Wow blast from the past .

I wonder just how much ice was in the inch of snow .

Even studded tires can break traction in the ice

Automatic Transmissions can be interesting as well

muddpigg

iTrader: (1)

Best thing for snowy conditions is slow and steady. Like Bill said "don't get over confident."

Just got back from a wheelin trip. Lake effect snow turned an 1.25hrs drive into a 2 hr drive. Wouldn't you know it as we're getting on the interstate there is a 3 car MVC, no causalities I checked. Seemed prudent to drive slow but as soon as we get clear of the collision cars start flying by us. Bit further up the road one of them is on the otherside of the ditch from the road. FD was on scene so didn't bother checking on them.

As mentioned in the right conditions even studded tires will loses traction. Drive to the conditions not the limitations of your vehicle. Anything else is idiotic with Darwin recommending to get out of the gene pool.