directional tyres running wrong direction

[Steptoe]

has anyone done this?

I have put my spare set of tyres on the Brumby shod with never run  no name Chinese on the rear and 2003 Bridgestone Potenza GIII on the rear

last time I ran the G3s on the rear they lived up to the Potenza name. I had other cheap Chinese on the front that were in need of renewal at the time

somehow the fronts had 39 one side, 31 the other. rears 31 and 32

bloody thing was tracking and felt like the whole set like marshmallows, with occasional mind of its own tracking like steering issues

adjusted them all to 36 and things are improved but still a little concerned about handling

fitting the new Potenza RE003s to the main set I notice the sticker states they are non directional but have an INside and an OUTside which is understood. What I didn't realise is that the old Giii were directional but not INside OUTside types. I was checking the make date numbers and spotted these arrows facing the wrong way !

Tomorrow will be left to right swap for the fronts to see wat difference it makes. You can read all sorts of tripe on the internet and this topic is full of opinions. One comment is that doing this arrow going wrong way can have significant affect on handling performance. At this stage I am prepared to believe this is so and not the combo of quality old tyres and new er..questionable quality tyres

 

In all the decades of tyres I have bought, I have never bought a second set of a particular style until now.

These Bridgie Potenza RE003 are a firm side walled tyre. Stick like baby poo to a blanket , wet or dry, makes no difference. And 50,000 km and still shy of the tread wear indicators

In 195.50.15 not too bad to remove or fit to 6 ich rims - with the right machine .

 

I will return to report my findings on correct direction, but curious of others experiences with directional fitment gone arse about

[1 Lucky Texan]

just speculation;

I can only imagine a difference (and it may be slight) with clearing water so, maybe one direction and hydroplaning happens 1mph, 3mph, 8mph, ??? sooner/later than reversed?

I suppose also, the tread design near any 'blocks' at the shoulder could have some difference in snow/mud?

on dry pavement, I doubt anything could be noticed other than 'maybe' road noise.

[el_freddo]

Pretty much what Lucky texan said: I believe the direction of rotation is optimal for acceleration and especially for braking. 

You wont notice any difference when cruising along, mainly when braking - and moreso in the wet. Block shape/placement and the diagonal slits all play a part in the grip provided. Most of it will come down to braking. 

Nachaluva was running a 4wd tyre backwards on our last couple of trips and there was no issue with that corner loosing grip over the other tyres being runnin the correct direction. Mind you, this was on dry clay/rock with one section of boggy mud that he did in a huge hole. No issues. 

Running tyres from 2003 is more concerning if they’ve been left out in the sun etc. 

Cheers 

Bennie

[Numbchux]

Results will vary considerably from one tire to the other. Usually it's just a matter of water clearing, but I could absolutely see it leading to strange handling characteristics.

[Steptoe]

I forgot to mention this being mostly a tarmac warrior due to the 50 series profile. I can almost imagine most tyre tread design of tar tyres goes out the window on anything less than tar or concrete. Have already discussed In and Out style tyre with a mechanic who trained with a tyre centre. Explained them as the road water squishing outwards. But I question what is wrong with water squishing inwards. Surely that is still getting water away from traction surface? Stumped him Not that I set out to do so. Sipes Bennie, sipes, is tyre tech for slots . I was surprised as to how good the Bridgies were when I worked out they had to be ten years old. Got them off a turbo Vortex hasbeen, that was shod with new shoes and never driven, though some ADHD medicated dude saw fit to cut a square hole in the sidewall of the rear 205.50.15 boots to recover the metal tubeless valve body, rendering a perfect new decent tyre - useless. Fast forward six years and these once near new tyres still look healthy. I know of some now 20 year old Yokies on my old Ford still look pretty good. It was the valve tits that gave way after 17 years. Cannot say the same for the cheaper to buy Chinese bags that turn a funny blue colour after twelve months. $50 for cheap Chinese versus $90 for Japanese brand made varyingly in Japan, Indonesia and this new set - Thailand. That extra $160 a set is very cheap peace of mind over the cheaper donuts that want to slip at the sight of a slight bend in the damp road

First task this morning will be to swap sides 

[Al Zhiemer]

The average life span of a tyre is a maximum of 6 years as recommended by the manufacturer, regardless of the condition of the tyre, even brand new tyres that have never been fitted. I'm pretty sure that here in Australia, it is even illegal for a tyre dealer to sell tyres older than five years old. In the case of an accident and an insurance inspector that knows his stuff, discovers tyres older than 6 years fitted to your vehicle can be enough to make your insurance null and void.

 

 In most cases but not all, it is about the outer blocks on the tyre, usually they will have larger blocks on the outside of the tyre, this is to create stability in cornering as a smaller tread block will allow the tread to move around under cornering load. A lot of tyre manufactures actually use a staggered outer tread pattern, for several different reasons, starting with smaller blocks and increase in size in several different stages. This allows them to have the best of both worlds, more sipes for clearing water, larger blocks to help prevent the tread from moving and also helps in reducing road noise created by the tyre.

 

Thats my understanding of it anyway.

 

And even with 50 series tyres, I'd suggest that 36 psi is to high and would probably drop back to 32 psi as there isn't a whole lot of weight on the tyre to make it bulge/flatten out. Higher pressures won't allow the contact area to maintain grip especially in cornering situations because there is no give in the sidewall allowing it to flex under load, just like low pressures can have a negative effect on vehicle handling, so to can over inflation. Start playing with cold tyre pressures a bit more as tyres will react differently to both pressure and weight, sometimes even half a psi can make a world of difference and enable you to find the sweet spot for the tyre and vehicle combination. Same as winter and summer temperatures can have an effect on what pressure you should be running.

 

Cheers,

 

Al

Edited April 13, 2019 by Al Zhiemer

[Steptoe]

all good comments Al. Just thinking back to roadworthy vehicle inspection manuals, training and reference and possibly the federal government issued stuff over the years - nothing on the age of the tyre and how to decode the numbers ( 3903 suggests 39th week of 2003) for validity to be used on our roads. It could be an interesting topic to raise with insurers, especially insurers of the older classics and vintage cars. So yet to read officially of this well spread theory. Some of the best fun I had as a younger driver was with a pair of 225.60.13 Yokies well aged, off a V8 Torana then shoved under the bum of my Maz1300 2 door wagon, 205.60.13 up front. They were ancient, had loads of rubber, hung on when needed, let go with a squeal when ask of on this amazingly well balanced little beast

The higher pressure use comes from those who I know to have been through er,,,specialist driver training and also a pair of them, the trainers themselves - to get maximum performance safety from the tyre. The only wear issues I have had is from neglected inner tie rod replacement or bad ball joints. The adjustable camber kit install seems to have righted a few wrongs as well .

First drvie with tyres rolling correct way - feels markedly different and better. I need to put down some specific roads to know better, then swap new to front, old to rear

[Al Zhiemer]

Correct, 3903 is decoded as you stated.

 

I'll have a dig through my book collection oneday when I'm home and have the time but I have a book I bought several years ago, it's part training manual that goes in to a lot of detail about tyre technology but its best feature is that it lists pretty much every rim and tyre combination that was available for almost everything that roles on tyres. Stud patterns, offsets, rim diameters and widths are all listed, is a fantastic reference for checking what rims will fit what cars. When I can dig it out, I'll get the name of it and where you can purchase it from if anyone is interested.

 

Cheers,

 

Al

[Steptoe]

there is a book by Emjoy with a lot of info. I have only read snippets and scanned through the nominal overall tyre diameter data . Was it this book yo mentioned?

Done the front to rear swap with the old Potenzas relegated to the rear, brand new Chinese up front. Totally different car to drive. So it wasn't the directional thing totally causing the problems

[1 Lucky Texan]

It's OK to mix tire models like that on your car? No torque bind?

[el_freddo]

 

32 minutes ago, 1 Lucky Texan said:

It's OK to mix tire models like that on your car? No torque bind?

Being a brumby/brat it’s front wheel drive unless you engage 4wd. So no binding under normal driving conditions, and when using 4wd it wouldn’t matter - terrain would make up for it or you wouldn’t notice it on dirt roads with the changes in surface, corrugations and potholes. 

Cheers 

Bennie

[1 Lucky Texan]

I wasn't sure so, thanx

 

[Steptoe]

 neither is Bennie so sure...this is Steptoe we are talking about. The difference in tyre performance and construction was not a consideration while in thrift mode. This Brumby/B.R.A.T. / MV1800 is EA82T flat manifold and AWD with locking centre diff, so the centre diff would be taking care of any diff binding properties. Very pleased with the results of a dozen years of waiting, collecting, tinkering, distractions etc. Did a mountain pass climb a few times recently where a 3.2 litre V6 saw fit to pass the Brumby mid climb but essentially got in the Brumby's way on the way to the top at about the limit of its handling geometry ability and most recently from the same family - a 2000 Forester EJ20 thought he should pass the Brumby as steep climbs came but just did not have the puff to pass or even keep up - all within the posted limits.

If the Foz had an EJ22 it may have been a different story....

The last event was done on the mixed breeds, ages and etc of tyres too and did surprisingly well

[el_freddo]

If you’re running the locking centre diff AWD box ALWAYS run the same make and model of tyres with the same tread wear. 

If you wear out that precious centre diff you’re up the creek for parts unless you happen to find another one of these gearboxes with a good centre diff. 

And yes, I should’ve know. With your tinkering it wouldn’t have been factory. How good is the AWD in these things? 

Cheers 

Bennie

[Steptoe]

what? Not enough they are same size? Having run my GLTA I knew the Brumby had to be AWD or develop traction control for a FWD set up.

The torque in FWD would upset traction at certain moments even at light throttle cruising and encountering water run off across the road I would feel a slip

No more squealing on roundabouts or turn twisty turns

I shimmed the centre diff up to factory specs when I had the box apart so would hate to kill it

still waiting for another centre diff to finish off the first box I got caught with

 

Need to pull finger out on my EJ tinkering and get my EJ20 AWD in and running, then maybe freshen up the EJ22 wasting space in the shed

[1 Lucky Texan]

AWD (viscous center diff or, in the auto, wet clutch-pack) really needs the tires to have the same 'rolling radius' (Subaru says, 1/4" in circumference) so, even though the size may be listed as the same, more than  2 or  3/32" or so in radius can introduce driveline stress if one 'end' of the car is rolling fatser than the other.

if you have open diffs at each end, you can run the pairs on opposite corners, or run the pairs on the same side as their mates and the open diffs will save the center diff.

 

some folks have taken the car to a large empty road/parking lot, marked the tires at 6 o'clock with chalk, roll straight forward for 10/20 revolutions of one tire, then compare each corner's offset from the other tires. do some calculations and you can determine if the tires are in spec.

but offroad or on wet roads, wouldn't matter as you said.

a true lock or unlock F or 4 wd center diff wouldn't care in FWD mode.

 

 

Edited April 19, 2019 by 1 Lucky Texan

[Numbchux]

When unlocked, that center diff is open, so it's not as bad as a LSD center like the EJ boxes. But yea, really should run 4 identical tires.

[1 Lucky Texan]

58 minutes ago, Numbchux said:

When unlocked, that center diff is open, so it's not as bad as a LSD center like the EJ boxes. But yea, really should run 4 identical tires.

 

Oh, if it isn't a viscous unit then I retract what I said.

I admit to being ignorant about the construction of the older soobs.

 

sry

Edited April 19, 2019 by 1 Lucky Texan

[Steptoe]

unlocked non viscous unit. I got it out of an EA82 wagon that was built up by staff of a Subi rally driver Andrew Penny who now has a daughter on the rally scene. The lock was never set up to work and I also took the same impatient install route - something I need to do before too much longer. Thinking something like a central locking door lock actuator might be simpler.

 

Got the LSD up in the bum too

 

The nominal tyre diameter could possibly be different or just the differing construction tolerances might be enough t upset things maybe.

 

I like the chalk stripe idea across the tread then roll to measure trick,,,,must have chalk somewhere_  thanks

[el_freddo]

9 hours ago, 1 Lucky Texan said:

Oh, if it isn't a viscous unit then I retract what I said.

But what you’ve said is very relevant. The old L series AWD centre diff is completely different to every other Subaru AWD diff setup - and they’re not common either! 

This diff will still wear out with miss-matched tyres. I’ve heard the outer casing is made of a material that’s a bit too soft for the job. Then some people do stupid things like drop this box in and not match the rear diff ratio, making the centre diff work overtime thus wearing it out. 

Then there’s those few idiots that rip on the front handbrake, lube up the rear tyres and drop the clutch to get their L series smoking the rear tyres. This cooks the spider gears in then centre diff - the indicator is discoloured (blueish colour I’ve been told) spider gears. I don’t know what drivability is like after the spider gears are baked. Probably not very nice. 

12 minutes ago, Steptoe said:

Thinking something like a central locking door lock actuator might be simpler.

That could work if it’s a strong unit, it can put up with temperature changes and other weather/road conditions such as water/mud/dust etc. 

You’d need a double spring setup with the diff lock arm between the two springs, the actuator pulls/pushes this spring device. This would allow the actuator to move to the desired position with the one of the springs pushing on the diff lock arm until things line up and it slots in. Once it’s slotted in you’d want the spring tension on the arm to be relatively neutral. 

I think that’s why Subaru went with the vacuum actuator - it can apply a pressure on the diff lock arm until the dog clutch lines up and it all slots in. If you’re not spinning a wheel or two you won’t even hear it engage, just the dash indicator light will turn on (if there’s no issue with the wiring - like on mine, broken wires at the switches on the gearbox). Some times when disengaging you will hear a thud in the drivetrain as some bind is released. I only ever lock/unlock on the move, never stationary. 

Cheers 

Bennie