Road Tyre vs A/T Tyre Off Road

[Rally]

To those who are set in their ways, do as you please. I doubt what I am going to say will sway your opinion. I make the following comments based on tens of thousands of kilometres of outback travel, and on terrain from gibber to rocky outcrop, mud, gravel and of course sealed road. Everything but sand and ice really.

I came to the conclusion after all those trips across the continent that to get a puncture, you really had to be unlucky. On one trip, we headed of down the Birdsville Track. It had just been re-opened following heavy rain. We were in 2WD vehicles and were the first vehicles to hit the track once it was re-opened. It was very muddy in places, especially the first half of it.Further on, my mate who was running all terrain tyres got a puncture. I was running road tyres, in this case 265/50's. I never got a puncture.

Of all the trips I did, from the Simpson, Sturts Stony, Tanami and other desers, and the Oodnadatta and Strzlecki Tracks, Buchanan "Hwy" (the West Australians have an evil sense of humour) and so many other tracks across the continent, I never got a sidewall puncture. Until I went to an all terrain tyre. Then I got a puncture on every single trip I did, without fail.

I came to the conclusion all terrain tyres are the most over rated thing you can get for your car. And while I have been stuck twice on my road tyres, my situation had nothing to do with tyres and everything to do with diffs. Yes, ultimately an all terrain tyre will hold a marginal advantage in off road traction, but nothing like the advantage the road tyre has over the A/T tyre on road. And even with a dedicated off road car, you still spend a far greater time on road than off. At least most people do.

So if there is minimal traction advantages, and punctures at best a lottery of luck (I am keeping L/T construction tyres out of this. They have issues of their own) at best, I would suggest spending money elsewhere on things that will make a real difference. I am. I'm spending money on getting a diff locker. I will only have to buy it once and unlike all terrain tyres, It won't adversely affect driving on road, and will do far more off road than an A/T tyre could ever hope to. Happy to do a side by side comparison after the car is back on the road with the new diff.

 

[jf1sf5]

I quite agree with what you write. I started with BFG AT's, then Grabber AT's and now have some Nokian AT's...the last ones being the less agressive by the looks.

A 4x4 tire specialist on forum4x4.org is allways telling everybody that the sidewalls are all equivalent in strength, what I don't really believe but he is probably right.

But how do you explain you had no puncture with road tires and so many with AT tires ? Did you drive differently thinking they are stronger ?

And for the traction, for sure a better transmission/suspension makes a bigger improvement over tires

 

[Rally]

I checked for myself the difference in sidewall thickness with thumb and finger. Not particularly precise, but the difference was big enough to notice. Road tyres need a stiff sidewall for cornering. I suspect, depending on the brand, that a/t tyres might be biased more towards sand driving and have a soft sidewall for bagging out when aired down. I drove no differently. I had no sidewall punctures on road tyres.

 

[MiddleAgeSubie]

There are two problems with your comment, Rally:

1/ It is one person. And your car is known to be not quite like the Subarus on dealer lots.
2/ Some AT tires have sidewalls that are far stronger than any street and many AT tires. You just lump all AT tires in one group.

You cannot seriously claim that a street tire has a stiffer sidewall than an LT-metric, 3-ply sidewall AT tire. In fact, my oversize KO2 corner just as well, if not better, than stock street tires. They do at par with the performance 255 55 18 street tires on the TB even though they are 225 65 17.

I can see how a 2-ply sidewall AT tire gives you no advantage over a GOOD street tire. Even here, however, your opinion would be of little use to me, if I were starting now. How in the world do I figure which street tire has good traction off-pavement? The street tires I have used off-pavement have been a joke compared to AT tires when it comes to handling and cornering. Next is longevity. All tires see their lives shortened off-pavement, but this is especially true of street tires. My Sumitomo on the B9 Tribeca looked like they were coming from a war theater at 28,000 miles. The Nitto 420S on the Tribeca are exceptional on road but a joke on dirt. None of my five sets of AT tires has suffered any chips or comparable damage and all have handled well (ATS) or great (KO2, Toyo Open Country ATII, Conti Terrain Contact AT).

So, I do not doubt that SOME street tires can do just as well as SOME all-terrain tires, but you cannot pass this as a universal conclusion (all street tires are same--or better!--than all AT tires).

So...
1/ one buys LT metric, 3-ply sidewall AT for strength. This is especially needed on a Subaru, which does poorly in rock and thus low pressures are essential and thus the aforementioned tires are essential, too. The Subaru needs some momentum where a Wrangler, Toyota, or Nissan can crawl. I am not driving narrow or rocky spots (see pics) on street tires, thank you. Further, the KO2 do great on road, performance wise. If one is driving narrow, mountain trail one should upgrade pads and fluid anyway; with upgraded brakes, the heavier, oversize tires are not a problem on road. Sure, they are harsher and make a bit of noise.

2/ One buys P-metric AT tires, like my brand new Conti Terrain Contact AT, for handling and cornering on dirt road coupled with less damage to tires from the ordinary crushed rock and gravel found on such roads. Instead of wondering which exactly street tire might happen to perform on dirt. On road, these mild AT tires behave just as well as very good street tires, so why not?

3/ Personally, I am beyond the one-tire suits it all approach. Now, I am getting beyond one car suits it all either, lol.

Pics:
examples of terrain I want the KO2s for

 

[Rally]

Please re read where I said I am not including LT construction tyres. My experience goes back 30 years and pre-dates my Subaru times. It includes comparisons with full size 4WD’s with experienced drivers, and in one instance a club off road driver trainer. It is not just my experience, although mostly it is. On numerous outings with others, new to the off road experience we have done off road trips without puncture. Last weekend was a good example. Gen 4 Outback, totally standard on no name street tyres. Spent all day on a particularly difficult track, especially for a novice, negotiating steep rocky conditions, water crossings and mud. Good opportunities for punctures and similar to where my at’s geolanders were punctured. He did get stuck once due to inexperience. However, I jumped in the car and drove it out. On the same trip, an SG on a/t tyres also got stuck due to inexperience and I drove that out as well. I have driven in more severe conditions but I reckon the majority of people on a/t tyres would not have. I don’t believe any a/t tres will grip on road as well as my 002’s or even come close. And I still maintain better diffs are a better solution, especially the locker going in my car shortly.

 

[Rally]

I see no problem taking my car, as is, to the places shown in your photos. Would be a good drive though!

On street tyres here. Too much for some of the A/T tyres cars. The 2 before me took 3 goes at least, including the club driving instructor. The other was a Pajero. Neither had a trailer. I was out first go.

 

[jf1sf5]

You have to take the driving skills as an important factor too, the most important in fact !

 

[Rally]

True. But in the photo above, one of the cars that took 3 goes was the clubs off road driving instructor. But remember one of the points I made above. Most of the people on off road tyres will not enjoy the marginal traction advantages because they either won't go to places that require it or their diffs will be the weak link and negate that small advantage.

 

[MiddleAgeSubie]

I cannot see that picture.

Yes, most people with AT or even MT tires do not need them any more than many people with Wranglers or trucks and big lift and tires do (most only go to the mall).

Yet, I still fail to see the point you are trying to make. Modern all-terrain P-metric tires like my Conti AT or the new Geolander GO15 have no downsides on road and yet guarantee good performance and tire integrity off-road.

How exactly does someone who is just starting figure out which street tire might have good dirt road traction? And how does one know which street tire will resist chipping?

If you want to go on shallow thread street tires on a narrow mountain trail, it is your choice. A Subaru can be pretty poor even in snow, its favorite element, on the wrong street tires. Similarly, if you want to expose your weak sidewalls to rocks, it is your choice. A stock Subaru on street tires and street pressures has close to no chance of climbing the small step on the first picture I showed you unscathed. And how long will aired down street tires last in that environment? Best case, they will all be chipped up. The Sumitomo tires of the B9 never saw anything that challenging and still looked like the craters of the Moon.

So, I still do not understand your advice or its target audience. If all all-terrain tires today were like my two sets of the old Geolander At-s, an awful tire in corners or hard braking, I would understand. But modern ATs do great on road.

 

[MiddleAgeSubie]

Btw, I am not trying to convince you. I just want to ensure that whoever comes across this on the internet has more info on which to base a decision.

 

[Kevin]

your car is known to be not quite like the Subarus on dealer lots.

:ebiggrin: yes, far from stock indeed! Lots more power and great traction control and will be awesome with rear diff lock for sure!

Rally has been very lucky with his use of road tyres in the outback e.g. I did the Gibb River Rd last year and witnessed heaps of vehicles with damaged tyres so thinking I might have a problem I asked a local tyre repairer about the issue "bloody road tyres" was the response! Apart from the original Yoko Geo AT, which were rubbish, I've been running BFGs on both cars (ATs on the Foz and MTs on the Triton) and, fingers crossed, have had 3 punctures that I can recall. Two of the punctures were in the outback and one of those was an Old Ghan railway spike that had come up through the Oodnadatta Track and ripped the sidewall, so yes, as Rally says, luck plays an important role!

I've travelled the Old Telegraph Track twice, including the Gunshot and Palm Creek crossings and I just cannot envisage any vehicle with road tyres successfully negotiating this track in the same conditions - but any attempt could prove very interesting!

"horses for courses" I guess.

 

[MiddleAgeSubie]

I think it is fair to say that Rally has built what Subaru should have offered as an optional trim. That's one awesome Forester, no doubt.

 

[NachaLuva]

Everyone is entitled to their own opinion but a few things must be taken into account.

Comparing the puncture resistance of tyres cannot be done from the experiences of one person, that's not how statistics work. It must be done with a reasonable "sample size", in the case of AT tyres the sample size is huuuge.

Opinions from 4 or 5 decades ago, while very interesting, have no relevance to now. The only similarity between tyres then & now is that they're round & black

Lets understand a few things first. All terrain tyres are designed for offroad work. This means they are designed to have tougher sidewalls & better treads for grip in slippery offroad conditions. This isn't an opinion, this is stated fact from every tyre manufacturer, it's also very obvious logic. You don't design a tyre that gets used in mud to have less traction than a tyre used on bitumen. Likewise, you don't design a tyre that gets driven regularly on sharp rocks, sticks, etc to be MORE puncture prone than a tyre that only experiences a smooth black top.

Lets look at treads. The tread pattern with the most grip offroad in most conditions (except sand) is a full muddy with large transverse blocks. Think tractor tyres. Why don't tractors run highway style tread patterns? Because they would get bogged every time they went out into a soft muddy paddock. Disadvantage is reduced grip onroad & very noisy. So we have all terrain tyres to fill the gap between hardcore muddy & road tyre.

An AT will have a more aggressive tread pattern than a highway terrain (HT), this will give more grip in sub-optimal conditions like wet gravel roads, loose gravel, wet clay, rocks, even mud. They are designed to be self cleaning (they throw out mud & small pieces of gravel as they spin). All tyres, even muddies, will clog up in thick mud, making the tread like a slick with virtually no grip. Muddies do this the least, ATs in the middle & HTs are virtually useless in thick mud

Road tyres need a stiff sidewall for cornering. I suspect, depending on the brand, that a/t tyres might be biased more towards sand driving and have a soft sidewall for bagging out when aired down

It's actually the opposite. Road tyres have a very flexible sidewall & AT tyres less so (not incl LT construction, which is obviously much stiffer again). This is because AT tyres are made to be more puncture resistant with stronger sidewalls, they also usually have some sort of tread or grip on the lower sidewall, adding thickness so adding stiffness too.

Many people, esp the WA guys who drive predominantly on soft to very soft sand, prefer road tyres to ATs as road tyres have more flex in the sidewall & bag out more when aired down. This combined with the less aggressive tread helps the tyre float over very soft sand instead of digging through it.

Now lets look at touring the outback on rough corrugated roads surfaced with countless billions of sharp jagged stones. Tyre companies do a huge amount of testing in these areas because it's such a great way to test in a large variety of conditions & those conditions are so severe. Discount everything from 4 decades ago, it's simply not relevant to now. It's like saying in the 70s I had a bad experience with one brand of oil so I'll never use it again. Oils & tyres are made from the same stuff & have dramatically changed!!

There are literally 100s of 1000s of vehicles, both 4wds, utes, & cars that drive the outback roads every day. This is a huuuge sample size to collect data from. I would love to see the ratio of ATs to HTs to road tyres used plus the puncture rates. I don't know if anyone can find this but it would be very helpful.

 

[MiddleAgeSubie]

Great synthesis, NachaLuva.

The tractor point is great; also desert rally machines use exclusively off-road tires. They cannot be accused of taking form over function.

 

[jf1sf5]

I think that what Rally says is that road tires are not having more sidewall punctures than AT tires when driving offroad.

I can't give my opinion because I always had AT tires and only had one puncture, it was on the sidewall of a Grabber AT.

 

[MiddleAgeSubie]

The point is that this is not a color or a season to be a matter of opinion. One person's experiences are irrelevant, statistically, and so are tires no longer on the market.

 

[Rally]

I cannot see that picture.

Yes, most people with AT or even MT tires do not need them any more than many people with Wranglers or trucks and big lift and tires do (most only go to the mall).

Yet, I still fail to see the point you are trying to make. Modern all-terrain P-metric tires like my Conti AT or the new Geolander GO15 have no downsides on road and yet guarantee good performance and tire integrity off-road.

How exactly does someone who is just starting figure out which street tire might have good dirt road traction? And how does one know which street tire will resist chipping?

If you want to go on shallow thread street tires on a narrow mountain trail, it is your choice. A Subaru can be pretty poor even in snow, its favorite element, on the wrong street tires. Similarly, if you want to expose your weak sidewalls to rocks, it is your choice. A stock Subaru on street tires and street pressures has close to no chance of climbing the small step on the first picture I showed you unscathed. And how long will aired down street tires last in that environment? Best case, they will all be chipped up. The Sumitomo tires of the B9 never saw anything that challenging and still looked like the craters of the Moon.

So, I still do not understand your advice or its target audience. If all all-terrain tires today were like my two sets of the old Geolander At-s, an awful tire in corners or hard braking, I would understand. But modern ATs do great on road.

You said above you don't see the point I am trying to make, having in your first paragraph responded to one of the points I was making. And it is indeed a critical point, which I don't understand why you dismiss so readily. I run Bridgestone RE002 tyres and have done so since they came out. I KNOW a Yokohama ATS will NOT grip ANYWHERE near as well on road as the 002. Why, because I have driven on both, owned both. The 002 will brake substantially better and corner substantially better. I have measured the thickness in their sidewalls, and I know which one has the thicker sidewall. I have no idea about driving on snow and ice, so let's leave that aside.

So how does someone know which street tyre to use? The same way they do to find out which A/T tyre to use. Ask. Well, no need, I have just told you. My target audience is the vast majority of of off roaders who want to make their cars better off road and who want to have the best compromise between off road ability and on road ability, with safety thrown in as well.

You say a road tyre wold not emerge unscathed in conditions shown in your photos, but the first 2 look very similar to where we went on Saturday. The bloke who had the SG with the latest ATS 15 Geolanders reckons they are so unimpressive on road, he is getting dedicated road tyres/rims and will only use the A/T's when off roading. I can understand why.

 

[Rally]

:ebiggrin: yes, far from stock indeed! Lots more power and great traction control and will be awesome with rear diff lock for sure!

Rally has been very lucky with his use of road tyres in the outback e.g. I did the Gibb River Rd last year and witnessed heaps of vehicles with damaged tyres so thinking I might have a problem I asked a local tyre repairer about the issue "bloody road tyres" was the response! Apart from the original Yoko Geo AT, which were rubbish, I've been running BFGs on both cars (ATs on the Foz and MTs on the Triton) and, fingers crossed, have had 3 punctures that I can recall. Two of the punctures were in the outback and one of those was an Old Ghan railway spike that had come up through the Oodnadatta Track and ripped the sidewall, so yes, as Rally says, luck plays an important role!

I've travelled the Old Telegraph Track twice, including the Gunshot and Palm Creek crossings and I just cannot envisage any vehicle with road tyres successfully negotiating this track in the same conditions - but any attempt could prove very interesting!

"horses for courses" I guess.

Of all the people on this forum, Kevin is one bloke I know who has travelled extensively, so I respect his point of view. I can only go from my own experience which is itself extensive. I keep doing trips and every time I come back, no punctures. Nor does anyone else who has road tyres. It can just come down to bad luck.

 

[Rally]

Everyone is entitled to their own opinion but a few things must be taken into account.

Comparing the puncture resistance of tyres cannot be done from the experiences of one person, that's not how statistics work. It must be done with a reasonable "sample size", in the case of AT tyres the sample size is huuuge.

Opinions from 4 or 5 decades ago, while very interesting, have no relevance to now. The only similarity between tyres then & now is that they're round & black

Lets understand a few things first. All terrain tyres are designed for offroad work. This means they are designed to have tougher sidewalls & better treads for grip in slippery offroad conditions. This isn't an opinion, this is stated fact from every tyre manufacturer, it's also very obvious logic. You don't design a tyre that gets used in mud to have less traction than a tyre used on bitumen. Likewise, you don't design a tyre that gets driven regularly on sharp rocks, sticks, etc to be MORE puncture prone than a tyre that only experiences a smooth black top.

Lets look at treads. The tread pattern with the most grip offroad in most conditions (except sand) is a full muddy with large transverse blocks. Think tractor tyres. Why don't tractors run highway style tread patterns? Because they would get bogged every time they went out into a soft muddy paddock. Disadvantage is reduced grip onroad & very noisy. So we have all terrain tyres to fill the gap between hardcore muddy & road tyre.

An AT will have a more aggressive tread pattern than a highway terrain (HT), this will give more grip in sub-optimal conditions like wet gravel roads, loose gravel, wet clay, rocks, even mud. They are designed to be self cleaning (they throw out mud & small pieces of gravel as they spin). All tyres, even muddies, will clog up in thick mud, making the tread like a slick with virtually no grip. Muddies do this the least, ATs in the middle & HTs are virtually useless in thick mud



It's actually the opposite. Road tyres have a very flexible sidewall & AT tyres less so (not incl LT construction, which is obviously much stiffer again). This is because AT tyres are made to be more puncture resistant with stronger sidewalls, they also usually have some sort of tread or grip on the lower sidewall, adding thickness so adding stiffness too.

Many people, esp the WA guys who drive predominantly on soft to very soft sand, prefer road tyres to ATs as road tyres have more flex in the sidewall & bag out more when aired down. This combined with the less aggressive tread helps the tyre float over very soft sand instead of digging through it.

Now lets look at touring the outback on rough corrugated roads surfaced with countless billions of sharp jagged stones. Tyre companies do a huge amount of testing in these areas because it's such a great way to test in a large variety of conditions & those conditions are so severe. Discount everything from 4 decades ago, it's simply not relevant to now. It's like saying in the 70s I had a bad experience with one brand of oil so I'll never use it again. Oils & tyres are made from the same stuff & have dramatically changed!!

There are literally 100s of 1000s of vehicles, both 4wds, utes, & cars that drive the outback roads every day. This is a huuuge sample size to collect data from. I would love to see the ratio of ATs to HTs to road tyres used plus the puncture rates. I don't know if anyone can find this but it would be very helpful.

If you are going to count statistics, you do not count the number of people on a certain tyre, but the distances they have done.

I did not form my opinion 4 or 5 decades ago. I formed my opinion having had so many punctures with A/T tyres about 5 years ago.

While I concede that the A/T tyre has an edge in traction off road (See first post this thread) I disagree with regard the sidewall. Why? Well, firstly I have checked the difference with the tyres off the rim and found the road tyre had a noticeably thicker sidewall. You are wrong to say that the A/T tyre has a stronger sidewall for the reason MAS stated above- different tyres will have different characteristics. I can only compare the Yokohama and the RE002. Why did the ATS have a thinner sidewall? I don't know, but it does. Perhaps as I said above it is designed to bag out more for sand driving. Other A/T tyres might be more biased to rock driving and have thicker sidewalls. The Bridgestone 697 does, because I checked that one at the same time.

There is a big difference in tread patterns and how aggressive they are amongst A/T tyres. Even so, in mud they soon fill up. We saw that with Chris with his super aggressive A/T's at Meryla SS not that long back. I have lost count of how many bogged cars like Chris there have been with A/T or even M/T tyres. No matter how good the tread is, there is a limit to how much they can self clean. The difference between the ATS and 002 is in this regard not that big. Which is why I showed you that photo in another place of your car and my car, both bogged requiring a tow out. You were in a river bed at an angle, I was in a mud hole at perhaps an even greater angle.

As I said, I do trip after trip after trip in a wide variety of conditions and I am still to get a sidewall puncture. No doubt one day I will. Maybe I might get 2 or 3 in a row. Now that would be bad luck. Still happy to go to a place and compare my car on road tyres to someone on A/T's.

 

[Rally]

Great synthesis, NachaLuva.

The tractor point is great; also desert rally machines use exclusively off-road tires. They cannot be accused of taking form over function.

I have built a gravel spec rally car, competed at international level in that rally car. I know that in that environment compound and construction is vital. I even tried rally tyres on my Forrie, but the noise was objectionable even at 60kmh. But no one off roading is going for a stage time. Just as I run high performance road tyres and not racing slicks or R spec tyres on my WRX.