Tyre Recommendation thread

[JohnL]

Just checked my pressures, they are 36psi. The 34 was when the tyre place filled them when they were not on the car.

My understanding is that tyre pressure difference with and without car weight on the tyre is fairly insignificant, typically in the order of 0.5psi higher with car weight.

Going too high tyre pressure on sydney roads = more lower back pain for me. Plus, my interior will shake itself apart.

Wuss, you need to toughen up! I grew up in Sydney so know the road conditions. Used to drive around Sydney in a 'Nota Sportsman' (poor man's Lotus Super Seven). This car had almost rigid suspension due to light weight (500kg) and dampers that were always far too stiff. Just couldn't find dampers soft enough unless I spent a fortune on proper adjustable racing units!

This car was truly bone shaking, but boy did it handle!! (accelerated pretty damn hard too!). The problem with really excessive damper rates as on this car is that the car will grip and grip and grip, then let go big time with no warning whatsoever because you ran over a gum nut or something (embarrasing at the very least!).

I already have stiff suspension with pillowball mounts, so it is now all down to the tyre. I guess that is what you get with an asymmetric design with nice blocks on the shoulders but crap all and drainage channels in the middle.

Hmmm, could possibly be zeroing in on the problem(?). Are you running much neg camber?

I assume these tyres have larger tread blocks with narrow and / or few channels toward the outer edge and smaller blocks with wider and / or more channels (and sipes?) toward the inner edge? They are also on the softer side re rubber compound?

The smaller the tread blocks the more they'll tend to squirm around. The more channels (and sipes) the more the blocks will tend to squirm around. The wider the channels the more the blocks will tend to squirm around (because with wide channels the blocks can't as easily 'lean' against each other for support).

The softer the rubber compound the the more the blocks will tend to squirm around, adding to any problem that may be caused by a more open tread pattern (but also meaning that as a general principle a softer rubber will be a bit less responsive than a harder rubber, all else being equal).

These factors will subtract from tread stability and steering response because there will be a tendency to run at a higher slip angle, and probably more so with increasing neg camber as this will tend to place slightly more static load toward the inner parts of the tread (where block stiffness is less robust) and less load toward the outer parts of the tread where block stiffness is greater. This is less than ideal (with such a tread pattern) for initial response before any significant body roll has developed.

Things get better for the outer tyre as it gains pos camber with body roll in corners (i.e. slip angle is likely to decrease), but worse for the inner tyre. This is less bad for a double wishbone suspension with decent camber gain curve, worse for a Mac strut with a crap camber gain curve (and the camber curve for a Mac strut typically gets worse if the car is lowered).

At high lateral Gs most weight transfers to the outer tyres, so in this state its not all that bad (with the outside tyre at increased pos camber and more weight thus being carried on the stiffer outer part of the tread pattern), but from zero weight transfer up until a high weight transfer has been achieved its less than perfect. Keep in mind that a front drive car set up to handle well will tend to unload the inside rear a lot and the inside front not a lot (relatively speaking), so until we see quite substantial lateral Gs the inside front will still be carrying a substantial proportion of front weight.

Some types of assymetric tread patterns may be a reasonable compromise for a tyre used in the wet and dry, but not necessarily all that great in the dry. The front tyres on my car have fairly small tread blocks, but the channels are quite narrow so when a block distorts at least its able to lean up against another block(s) for some increased support. The rubber is also a bit on the hard side which means a bit less block squirm, which is good for steering response though of course isn't all that great for outright grip.

I don't mean to imply that all assymetric tyres are crap, just that an assynmetric tread is a compromise of which I'm not much of a fan in general principle.

[aaronng]

My understanding is that tyre pressure difference with and without car weight on the tyre is fairly insignificant, typically in the order of 0.5psi higher with car weight.

It was a 2psi increase in this case (1395kg car). I'm just reporting what I found when I had RE001s put in 2 weeks ago. I'm not making numbers up.

Wuss, you need to toughen up! I grew up in Sydney so know the road conditions. Used to drive around Sydney in a 'Nota Sportsman' (poor man's Lotus Super Seven). This car had almost rigid suspension due to light weight (500kg) and dampers that were always far too stiff. Just couldn't find dampers soft enough unless I spent a fortune on proper adjustable racing units!

You're not the one with a mild slipped disc in the back.
Edit: I just increased the tyre pressure from 36psi to 40psi. Response has improved a bit. I was surprised that the RE001s were rated to 51psi in 205/55 R16, higher than the S02's 41-42psi in the same size.

Hmmm, could possibly be zeroing in on the problem(?). Are you running much neg camber?

Nope, everything is within stock specs except for the front toe, which is 0.6mm total toe out.

I assume these tyres have larger tread blocks with narrow and / or few channels toward the outer edge and smaller blocks with wider and / or more channels (and sipes?) toward the inner edge? They are also on the softer side re rubber compound?

They have large blocks on the outer shoulder and slightly smaller blocks on the inside shoulder. The middle has 2 ribs and a wide band of blocks. It shouldn't do what I am experiencing, but maybe the sidewall is just soft. Here's a pic of the tread;

The softer the rubber compound the the more the blocks will tend to squirm around, adding to any problem that may be caused by a more open tread pattern (but also meaning that as a general principle a softer rubber will be a bit less responsive than a harder rubber, all else being equal).

That could be the case.

[aaronng]

Hey everyone, a couple of questions
1) Bridgestone RE050's come in two types RE050 and RE050A, besides from one being symmetric and one being assymetric, what's the difference? is the assymetric one much better? it always seems to be the one used in tyre tests.

2) How much of a concern is it that the RE001's don't come in left and right versions?

1) One is assymetric and the other isn't. That's the difference. They are soft tyres though. Only a 140 wear rating, like the S02.

2) Not a concern to me. No pulling to the side so far.

[JohnL]

It was a 2psi increase in this case (1395kg car). I'm just reporting what I found when I had RE001s put in 2 weeks ago. I'm not making numbers up.

I don't mean to suggest you are making the numbers up. I haven't actually tested this personally, my number (0.5psi) comes from a post on the Eng-Tips engineering forum (a great forum for the technically minded, largely populated with proffessional engineers, check it out).

The poster did the experiment with a heavy car, and thats what he found in that case (though I'd be surprised if it differed much case to case). The comparison needs to be made back to back with the same guage and the tyres at the same temp, if not then then the test isn't valid.

It doesn't take much temp difference to make a measurable difference in tyre pressure (i.e. 'cold' pressure on a cold day compared to a warm day), and different pressure guages can vary a lot one to another, and a cheap guage may even give a different reading depending on temp (i.e. ambient temp difference may cause a rubbish guage to read differently even when the psi is actually the same). I used to have one of those 'pen' type pressure guages that would give a different reading every time I used it (within about a four psi range), even if there was only a few seconds between each use!

You're not the one with a mild slipped disc in the back.
Edit: I just increased the tyre pressure from 36psi to 40psi. Response has improved a bit. I was surprised that the RE001s were rated to 51psi in 205/55 R16, higher than the S02's 41-42psi in the same size.

I used to get a pinched nerve in my lower back on a regular basis, so you have my sympathy. I'm lucky, the aging process seems to have largely fixed this problem, or maybe its because I sold the semi-rigidly suspended Nota!!

So with the higher pressure, is the ride significantly any more unbearable?

I still think 10% below max reccommended psi (tyre manufacturer, not car) is the place to start experimenting with psi. This is a rule of thumb I've read on a few places on the net (so it must be right, right?), and even though I was a bit sceptical, funnily enough this is about where I've ended up with my psi after a lot of experimentation!

A max pressure rating of 51 is becoming more and more common. Not sure if this is because of any physical changes in tyre construction, or whether the tyre companies are just becoming increasingly more confident that this is a safe working pressure (keeping in mind the potential for litigation etc). It may just be some change in the regulations covering how a manufacturer comes up with things such as reccomended psi etc?

Note that a car tyre will be nowhere near its burst point at 51 psi, that will be well over 100psi. Also, the max reccomended pressure is a cold pressure, if the tyre goes over this when it warms up then thats OK and the tyre manufacturers take this into account when setting their max reccomended psi.

Nope, everything is within stock specs except for the front toe, which is 0.6mm total toe out.

I'm not sure that a difference bewteen say zero and 0.6mm toe will make a 'feelable' difference to steering response, stability etc, but stranger things happen!

Yesterday afternoon I replaced two very slightly flogged out rear ARB link rubber bushes on the CB7 (with new poly items), fully expecting to be able to feel zero difference in rear roll stiffness, especially with such a soft ARB (only expecting to lose the slight clunking). Just drove it briefly this morning, and I'd swear I can feel more roll stiffness and less understeer (though the clunk is still there, of course...!). Might just be my imagination, but if not a huge one it does seem a marked difference...?

They have large blocks on the outer shoulder and slightly smaller blocks on the inside shoulder. The middle has 2 ribs and a wide band of blocks. It shouldn't do what I am experiencing, but maybe the sidewall is just soft. Here's a pic of the tread;.

Most tyres probably do have softish sidewalls, even many with performance pretensions. Most drivers don't really want to actually feel the road surface (even if they might think they want 'high-performance'). My experience is that above a certain point, increased pressure doesn't make all that much difference to how harshly you may feel a significant actual bump, but it does make a difference to how much you can feel rough surfaces, i.e. at the vibration and 'harshness' level rather than at the road bump 'impact' level. What makes a real difference to how hard you feel an actual bump is the damper stiffness, more so even than stiffer springs (though very much stiffer springs are probably a different story).

That could be the case.

I would expect the trye to become more responsive as the blocks wear down. Motoring journalists tend to like responsive handling etc more than the average driver cares (or think they care), so, I've neard that car companies have a habit of providing test cars to journos fitted with tyres that have been buffed to about half tread depth, but this may be a myth?

[JohnL]

Hey everyone, a couple of questions
1) Bridgestone RE050's come in two types RE050 and RE050A, besides from one being symmetric and one being assymetric, what's the difference? is the assymetric one much better? it always seems to be the one used in tyre tests.

Assymetric treads can provide good channeling on the inner part of the contact patch to more effectively clear water, but when grip is higher you can lean the tyre into pos camber (with body roll) and effectively have a tyre with less channels (for improved grip level) in that part of the contact patch that is working hardest (i.e. the outer part of the contact patch).

If you are running a lot of neg camber then when zero body roll is present more of the car's weight will be on the inner part of the contact patch where there are more channels and smaller blocks, so you may get slightly inferior steering response since the smaller blocks are less stable.

With some assymetric tyres the intent may be slightly different. With some assymetric treads the difference in the amount of rubber vs the number / size of channels is substantial, but with others there may not be nearly as much difference in the amount of rubber vs the amount of channels in different parts of the tread, just a difference the shape of the channeling. In theory such a tyre will have a tread pattern on the inside that is designed to give better longitudinal stability (i.e. steering response, tracking) and a pattern on the outer part designed to give better lateral stability (i.e. better lateral grip).

2) How much of a concern is it that the RE001's don't come in left and right versions?

Don't know. I like my tyres to be symmetric and uni-directional. This means I can place any tyre anywhere on the car I want, and if I have a steering pull that isn't caused by the alignment but by the tyres (conicity), then I can flip a tyre on the rim in an attempt to correct it. Note that this isn't likely to be a problem on more expensive tyres, though it could be.

When fitting tyres, if the new tyres have a line around the circumference then these lines should match between both tyres on an axle line. These lines represent the 'conicity' of a tyre, which has to do with any slight mis-alignment of the belts under the tread that can cause a 'pull' in the tyre. A quality tyre will be tested after manufacture in a machine that measures any 'pull' inherent in the tyre and the tyre is marked accordingly with the circumferential line. Some tyre fitters don't seem to be aware of this and will fit any tyre any old place in any old way paying no attention to the lines marked on the tyre.

If one tyre has a line around the centre of the tyre then conicity is zero, and the other tyre on the same axle line should also have a line around the centre. If one tyre has a line toward say the outer part of the tread then so should the other tyre, if the line on one tyre is toward the inner part of the tread then the other tyre's line should match. If not then don't be surprised if the car pulls to one side, even if alignment is perfect. My experience suggests that unmatched conicity of the rear tyres can cause a pull just as easily as if the problem were with the front tyres.

If the lines don't match front and rear, then if the tyres are ever rotated diagonally the car may pull. I never rotate my tyres, at least partially with this in mind.

[aaronng]

I used to have one of those 'pen' type pressure guages that would give a different reading every time I used it (within about a four psi range), even if there was only a few seconds between each use!

I used 2 gauges. A cheap metal case dial one, and a calibrated Jamec Pem. The cheap one was reading lower by 0.7psi when compared to the Jamec.

I used to get a pinched nerve in my lower back on a regular basis, so you have my sympathy. I'm lucky, the aging process seems to have largely fixed this problem, or maybe its because I sold the semi-rigidly suspended Nota!!

Hopefully my back sorts itself out or the chiro does. I rented a Yaris for a day and the seating position was so bad even after adjustment that I was back to almost square one when I returned the car!

So with the higher pressure, is the ride significantly any more unbearable?

Actually, I haven't had more pain. But I can feel everything in the car vibrating now, including the interior trim. I'll leave it at 40psi for the next few days to see if it is livable. But for now, the dead feeling in the centre is minimised by say 50%. There is still a dead zone that wasn't there with my old hard tyres, but I guess it is just because the new tyres are still soft.

I still think 10% below max reccommended psi (tyre manufacturer, not car) is the place to start experimenting with psi. This is a rule of thumb I've read on a few places on the net (so it must be right, right?), and even though I was a bit sceptical, funnily enough this is about where I've ended up with my psi after a lot of experimentation!

Yup, I read that too. But I was still wary of going for 46 psi on the street.

I'm not sure that a difference bewteen say zero and 0.6mm toe will make a 'feelable' difference to steering response, stability etc, but stranger things happen!

The stock specs for my car is actually 1mm toe in, which is for straight line stability. Even at that setting, the car tramlines and follows any road imperfection. I couldn't stand the lack of steering response in the middle, so went for a 0.6mm toe out and on the old Dunlops, it was sharp in the middle. I did have a short stint where the tyre place used their own alignment specs and had that 1mm toe in for a week and I really missed the 0.6mm toe out. Of course, they changed it back to 0.6mm for no charge the following week. Good bloke, that tyre place owner.

I would expect the trye to become more responsive as the blocks wear down. Motoring journalists tend to like responsive handling etc more than the average driver cares (or think they care), so, I've neard that car companies have a habit of providing test cars to journos fitted with tyres that have been buffed to about half tread depth, but this may be a myth?

I wouldn't be surprised. If companies are willing to send out "specially prepped" cars for journo reviews, I'm sure they'd take the time to just scrub the tyres out a bit on a 50km spirited drive.

[JohnL]

I used 2 gauges. A cheap metal case dial one, and a calibrated Jamec Pem. The cheap one was reading lower by 0.7psi when compared to the Jamec.

Aaron (I got that right?),
There's part of the difference. Was the tyre temp the same? I've seen a 1psi difference with pressures taken in the cool of morning and at midday, with the car not having been driven and in the shade.

Hopefully my back sorts itself out or the chiro does. I rented a Yaris for a day and the seating position was so bad even after adjustment that I was back to almost square one when I returned the car!.

Serves you right for renting a Yaris (where's your self respect man!).

FWIW, A very recent study suggests that most chronic spinal pain is more responsive to mild anti-inflammatory / pain relievers (e.g. Panadeine et al) and mild exercise than it is to more drastic medication, physio or other more intrusive treatmenmts. Not to say that this will be so in your case...?

Actually, I haven't had more pain. But I can feel everything in the car vibrating now, including the interior trim. I'll leave it at 40psi for the next few days to see if it is livable. But for now, the dead feeling in the centre is minimised by say 50%. There is still a dead zone that wasn't there with my old hard tyres, but I guess it is just because the new tyres are still soft.

Ah, well, yes, there is the co-lateral problem of increased interior buzzes etc with higher psi. This might be another reason why car manufacturers often opt to recommend such low pressures?!

On my car, on bumpy roads the higher psi excacerbates rattly buzzes that come from the air-con / vent control buttons on the centre console, I have to turn the CD / radio up to disguise it!

Seems to be happening in the buttons, but behind the visible face of the buttons, not in the bits you can touch (i.e. the real buttons behind the cosmetic ones, or maybe some little springs behind there or whatever?). I want to try and fix it, but I can't get the bloody console out, its defeated every attempt at removal! Must be more hidden fasteners somewhere, found some but can't find them all!

Yup, I read that too. But I was still wary of going for 46 psi on the street.

You don't know if you don't try. If its unbearable or car behaves badly then let air back out.

The stock specs for my car is actually 1mm toe in, which is for straight line stability. Even at that setting, the car tramlines and follows any road imperfection.

At zero or such a small toe out, my bet is that this is likely to be more a characteristic of the tyre itself than the alignment...(?).

I couldn't stand the lack of steering response in the middle, so went for a 0.6mm toe out and on the old Dunlops, it was sharp in the middle. I did have a short stint where the tyre place used their own alignment specs and had that 1mm toe in for a week and I really missed the 0.6mm toe out. Of course, they changed it back to 0.6mm for no charge the following week. Good bloke, that tyre place owner

Again, my guess is that it's most likely to be a tyre characteristic than an alignment issue, could be wrong.

Might consider trying a small toe out myself then if its affect is noticable, hopefully with no significant adverse impact on wear. I do my own toe alignment with string lines, takes about 40 minutes go to whoa, with practice, and once you've made the jigs that stretch the string lines (which are fine fishing line).

Stock spec on mine (from owners manual) is zero front toe. Stock camber is also zero, but I am running about 1° neg (I had to equalise it due to accident damage from previous owner, by increasing neg on undamaged side, rather than decreasing it to standard on the damaged side, my choice).

I also have increased caster, not sure exactly to what angle as I haven't measured it precisely (probably about 5° or 6°), all I know for sure is that its equal side to side (or very near to it). Standard CB7 caster is 3°, before changing mine it was 2.8° on one side but only 1.7° on the other (the accident damage, since rectified).

Substantially increased caster is a very worthwhile thing, but due to lack of proper adjusters just a bit of a pain to achieve! (and you need to know what you're doing because increasing caster can create a few hidden problems if you go too far). You can change caster by shims at the front suspension mount, but you can only increase it minutely by removing any stock shims, or decrease it by adding more. Beyond this you are modifying or changing parts.

Increased caster makes a big difference to on-centre feel and also benefits steered camber angle at both the inside and outside steered wheels, especially with bigger steering inputs in tighter corners. There is some increase in steering 'weight', but no big deal with PS, its actually nicer that way!

I wouldn't be surprised. If companies are willing to send out "specially prepped" cars for journo reviews, I'm sure they'd take the time to just scrub the tyres out a bit on a 50km spirited drive.

I meant actually scrubbed on a machine (abraded or cut), like some racers do with street spec tyres. I doubt you could 'scrub' off enough rubber in a 50k drive to make much difference... unless you were an absolute maniac!

[16CTEG]

LOL can someone kill this thread!! lol going forever!

[STTICH]

happens when some ppl have too much time.

interesting read tho.

[JohnL]

happens when some ppl have too much time..

Yeah, lifes a bit quiet just at the moment!

interesting read tho.

We try to entertain!

[aaronng]

Quick update. I couldn't live with 40psi. My pillowball mounts (especially the rears) were knocking over every little imperfection in the road. Basically, it was "knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock-knock" all the way and after 15 minutes, I pulled into the nearest petrol station and let some air out. Now I'm on 38psi front and 36 psi rear... My sanity is coming back.

[Killa From Manila]

got some quotes today.

195/55/15
firehawk wide ovals $144
re001 $164

195/50/15
wide ovals $109.

gonna put an order in 2moro, wats some quality tyres i shud ask for??
budget is around $150, mite go a little over maybe.