anomad

Hi folks, I am new to yotatech.com but have been 4 wheeling for work and play the better part of 20 years now.


I have done many searches here and on other forums for an intelligent discussion of tire size as a function of off road ability or capability with all else being equal.

Let's say we have a toyota with 235/75 tires and the same exact truck ith 33 inch tires (let's pretend the suspension/gearing/lockers aren't a factor here). How much better would the larger tires be off road?
In mud?
On rocks?
Water crossings?


I am currently driving a bone stock '03 regular cab. It amazes me to no end where it will go with careful driving. Unquestionably dual lockers, and self recovery ability would be my first upgrade to increase off road capability. But I would like to hear from folks on the forum how their experience with larger tires increased their off road capability.

d0ubledown

larger than stock gets you numerous advantages. 1 being of course the increased clearance gained underneath. Bigger tires also improve all your angles: approach, breakover & departure. The 2nd being the amount of sidewall and flex gained from airing down. We all know this helps the tire 'wrap' itself around rocks etc. However, bigger tire & airing down kind of cancels itself out, but its marginal the amount you lose when airing down.

Wider gives you better stability & more grip when the tires conform to the shape of the rockface..etc.

That said, its often if better to go with a size thats a good compromise. small enough to stuff in your wheel wells, but big enough to make a clearance difference. There is such a thing as too big...

91_4x4runner

Well, the extra clearance can help boatloads in water crossings (keeping intake above water). They will also have a larger contact pattern in the mud, which should allow for more traction. Typically, larger tires also have larger tread blocks, which would be another benefit. On rocks, the added height would give you better approach and departure angles. With larger tires, you also have more rim protection (aluminum cracks when hit hard (rocks)).

The only real benefit I see of the smaller wheels is the ability to get more tire spin (horsepower/torque limitations apply).

91_4x4runner

you mean like 53" boggers?

bob200587

Yes. I agree. or 20" rims with 37" tires.

fork

20"? planetaries i hope but i would like to see someone take some chrome blingy rims offroad, just so i can laugh at them when they get carved up

i'm assuming the tire tread is the same for both tires in this discussion.

i think larger tires really do make a difference for offroad capabilities. To a limit of course. I have a hard time coming up with places that i've been where larger tires wouldn't have made it a lot easier to get through. I think mud might be the only one that a smaller tire might not be as bad, but that also depends on the mud. Just to be able to spin them faster. I would still rather have larger tires for mud though. And definitely for rocks and water.

Elton

welcome to yotatech ..thats all i have to say

anomad

Thanks for the welcome.

So in my example 235/75 vs 33" tires a person would gain 2 inches of clearance. Doesn't seem that huge gains in performance could be expected.

norcalsvx

i just switched for a small size to 33" and it helps keep my axels up out of the snow it helped a lot off road

d0ubledown

2 inches is quite a bit all said n done & all other factors being equal. depends on what you expect 'performace' wise. as stated above in my first reply, that 2 inches could make a difference in an approach angle, getting over that rock or not, and breakover as well. it may not seem like a big difference on paper, but in real world testing, it will.

i went from a 31 (265/70/16) to a 33 (285/75/16) and it made a world of difference, even just in plain dirt roads with the occasional washout.

Elvota

Considering that sometimes less that 1" can stop a vehicle, a 1 or 2" gain is considerable.

High steps or bench type obstacles contacting low cross members or frame come to mind. Personally I have cleared said obstacles with 35's that caused others in the group to remain stuck with 33's.

I'd second (or third) all the above opinions on the benefits of larger size, but also understand the increased leverage a bigger tire places on your components. More leverage, more grab and more resistance all send a load to the next component. Axles, CV's, steering...

I have found that most people feel 33's work pretty well on IFS, but 35's are considered pushing things a bit. Just like a stock Toyota straight axle works well with 35's, but 37's start to cause problems.

These are not rules, there are always exceptions and work arounds, just seems to be the general consensus as far as I can tell. With upgraded components on either suspension system you can get away with a lot more.

53" boggers might be the exception.

AxleIke

This is a good discussion.

As far as a larger tire goes, more height gives you more clearance. This is ALWAYS good. Lift will get most of your truck up out of the rocks, tires will get your axles there.

Fatter tires have less traction. However, they have more area to "catch" on the rocks. So, while a fatter tire is more likely to slip, it is also more likely to catch again. Traction on rocks is a wash. On road, a narrow tire gives you much better traction. Fatter tires give you good stablility, and will widen your width, meaning you can tip farther before flopping.

Larger tires, as pointed out above, will increase wear on your components.

In mud, or deep snow, a fat tire is better. It has less traction, but that makes no difference in such a low traction environment. What helps you is the width spreads out the weight, and "floats" the truck, meaning you are less likely to drag axles, or worse, sink it up to the frame. A narrow tire will cause you to sink.

HaveBlue

I, too, went from 265/70/16 (31") to 265/75/16 (~32") to 285/75/16 (33") and each increase has made a difference. The biggest difference was between the 265/75 and the 285/75. I gained some clearance and greater surface area for off-roading.

How about some real world, side-by-side input...
A few years ago, I went wheeling with a couple people from YotaTech. Both of them had 33" tires. One had 33" Goodyear MTR, the other had 33" BFG Mud Terrains. While I had 265/75/16 BFG All Terrains. While I was able to keep up through most of the trail, I got hung up on a couple larger rocks in a rock garden section while they were able to roll through with minimal effort. That extra 1" made a difference.

bob200587

There was another thread about that issue earlier. And I think the general consensus was that in order to get tires wide enough for that to make a difference they would be absurd in width and also require copious amounts of power to effectivley turn. Therefore, in the realm of our small toyota's in say, a 33" tire, was an overall wiser choice in a 10.50 variety than that of a 12.50.

Basically the width would be great, but causes more woes without enough gain.

anomad

That is actually only one half inch on both sides of the tire, I suspect factors came into play in addition to the tires.



Interesting. Different vehicles though, it would be something to try a trail like that on 33's then try it again with 35's. A 4x4 rag should do and article like that.

I agree that larger tires are in fact better, just wondering how much better given the costs involved.

Specifically, I am looking at two used rigs right now. One is older and been totally built up with 33 BFG muds and the whole nine yards, 8 grand. The other is newer, bone stock 225/75's I think, but 3 grand less. I am trying to convince myself the newer rig would be the better purchase. Then using the extra money to stuff in lockers and buy a winch to take me farther down the trail.

It might be better for me to think about tires in terms of percent size larger. A 10% larger tire is only 3 inches, for a 30" tire. 1.5 higher off the ground just doesn't sound like much.

thralldad

I drive mine on the street more than offroad. 225/75-15s. Will a 30" or 31" tire affect the speedo?

anomad

Yes. Measure the circumference of the existing tires and then the new tires to calculate the difference.
Or if you have a GPS, that makes life easier.

Elvota

In my stated example, I was driving a 2nd Gen 4runner with a SAS, 4" lift and 35's. The other rig was a 1st Gen, straight axle, around 4" lift, 33's.

I snuck over the "bench", his crossmember did not. With some stacking and steering he was on his way.

The vehicles were by no means exact, but pretty darn close. Could he have taken another line and gotten to the same place... for sure. Did my 35's save the day... no, but they did give me more successful lines to choose from.

I don't think there would be many situations where only 35's or 37's could make it through an obstacle, but an inch here and an inch there of added clearance be it with a lift or tire size can add to the capability of ones rig a great deal.

anomad

When it comes to lifting and regearing if I am contemplating 33's with one lift or 35's with the same lift and a little trimming I would have the sawzall out before you could say "put on the 35's".

I can visualize the exact situation you are talking about. I got hung on a rock once in a creek with my '91 on that cross member.

AH64ID

In the past 6 years I have had two 86-95 IFS rigs, a 4runner and a p/u. The front suspesnions were the same, and after the leaf swap on the 4runner so was the rear... .From the getgo they both had 4.88's and a ARB rear... I have wheeled from 32 to 35" tires, from swamper radials, swamper bias ply, m/t's and a/t's.... So I have seen the "all else being equal"...

Larger tires make it much easer to do certain things, but the 32" tires I ran would have gotten my 95% of the places the 35's did, it just would have been much harder....