Bridgestone Adrenalin RE001 vs PP2 vs rest?

[Garry]

Both of my MX5's must be freaks then because if I ran 36PSI in either of them they were very skittish however they were fine at 30-32PSI. My previous car however (fixed roof) had no trouble with 36PSI, however the manufacturers recomendation for that car was for 32PSI, not 26 like for the MX5's.

[JBT]

I was starting to worry too Garry.

When I say "skittish", I mean just that - intermittent grip over uneven/choppy surfaces which becomes particularly noticeable when cornering regardless of how smooth the inputs may be. I have dríven the same road under the same conditions at the same speeds: at 36psi (and higher) pressures the DSC/TCS is activating all over the place = no grip. However, at 30-32psi no DSC/TCS activation = grip.

I suggest that Roadcraft get more life out of their tyres at extremely high pressure because there's less tread contact with the road surface. I take the point about skid marks under braking but have you considered that the skid started because the pressures were below recommended (too low) in the first place. I've seen plenty of skid marks with full tread width too - what does that mean? 44 psi cold would be running close to the maximum pressure allowed on some tyres when the tyre gets hot.

All tyre manufacturers seem to recommend an increase of about 10% over the recommended cold pressure for high speed/high load/towing conditions. Do you really believe that car manufacturers deliberately recommend a pressure that makes the car doughy (and thus dangerous) just to make it "comfortable" to ride in and that they are colluding with tyre manufacturers in some sort of conspiracy to cause tyres to wear out earlier

As for wear: I have done a full skid pan day, three track days and 22,000km on the Bridgestones (32psi cold) and the only tyres (outside quarter) that are worn a bit too much are the ones that were on the left side (too many right turns on the tracks here) because I didn't rotate them. The others have more than half tread depth remaining - so what does that prove?

I would still like to see some empirical (rather than anectdotal) evidence on grip comparisons at different tyre pressures.

Oh, and by the way NMX516, I won't comment on your driving style if you don't comment on mine - especially given that I don't recall riding in a car with you as driver or passenger.

[NMX516]

Oh, and by the way NMX516, I won't comment on your driving style if you don't comment on mine - especially given that I don't recall riding in a car with you as driver or passenger.

Ok John, I wasn't having a go at your driving style, or even commenting on it. I apologise if it came across that way, but it wasn't my intention to do so. I made the statement that if your (being anyone reading the thread) tyres are sliding more at higher pressures (thinking in a track day situation, as we have been talking pressures for track days - note I didn't say "skittish" as is implied as a road situation) then driver input could be part of it. Our tracks are generally fairly smooth surfaces, not the sort of potholed, chopped up surface that can easily be found on the roads. That's my thinking out aloud, bouncing ideas off forumites, wondering what sensible, thoughtful responses might arise from that idea - not having a stab at anyone! I wasn't saying that anyone here is a bad driver because their car slides more with higher tyre pressures - what I was trying to say is that if they are having that problem, it might be because they are used to driving at a certain style which requires more of a heavy hand because tyre response is a little doughy. Ergo, then with tyres that respond in a sharper manner could need a softer hand to corner smoothly... The "wink" at the end of my post was in the vein of "I think that would be worth trying, and hopefully it might solve the problem" not in the vein of "I know best and your driving style is rubbish" as you seem to have taken it as being.

Further more, I'm not going to continue to debate the theory of recommended tyre pressures. From what I've seen and been told over the years, I consider that they are best for me at 36 psi, so that's what I will run. John, Doug has also told me to start out with 36 to 38 and go from there. I'm going off what guys with a lot of direct experience have told me over time. I recall Doug asking me what size tyres I had when I did ask him. Perhaps 17's can get away with lower pressures, I don't know, I've never had a car with 17's. That is my experience, that is what I am happy with running my tyres at. I suspect that different tyres would be different too. I run 34 front and 34 rear in my Pulsar... 36 is not the magical number, but that is what I'm happy running in the MX5, with PP2's on. I also run that on the RE001's.

JBT you will run your tyres at 32 psi, and that's probably never going to change because I doubt anyone will be able to ever produce to you some empirical evidence as to why you might be better served with higher pressures. None of the manufacturers will ever do so, and looking at skid marks on the road will always draw the response of "but yesterday I saw some that were...". As far as I know, none of us here are forensic crash investigators, so no matter what any of us say, it's probably all just crap anyway.

Edit: oh, and while I think of it, I run my semi slicks at 28 psi cold. That is what has been recommended to me by various people with a lot of experience with those tyres. As I understand it, the reason is because the tyre is a stiffer construction than a normal road tyre, and so doesn't require as much air pressure to keep it in shape.

[Old Dude]

I know by looking at my OEM tyres ER30 being run at 30psi were wearing out on the edges, so obviously not enought air ,

since I upped it to 36psi on both them and now the 16 inch PP2 the car doesn't wallow, and I must admit the PP2 do give a comfortable ride, I just have to wear them in a bit and see what happens.

I got the wheel alignment when I put them on, and they put 36psi in them, as previously stated my only concern was that I had to turn the steering wheel more to get the same directional responce with these new tyres, and are waiting to see how they go once all the mould goo wears off.

Anyone know a good wheel aligner on the Gold Coast or Brisbane who specialises in our stuff.

Old Dude

[AJ]

Fulcrum Suspension is a Club sponsor Old Dude, & have done a lot of MX5's

[JBT]

Doug has also told me to start out with 36 to 38 and go from there. I'm going off what guys with a lot of direct experience have told me over time.

My points of discussion are related to everyday road use and not track. However, for every race experienced person that has recommended high pressures I've had another say the very opposite. I haven't been able to find any authoritative source (car or tyre manufacturer, motoring body etc.) that recommends anything more than about 10% above manufacturer's placard settings and then only for high load/speed conditions.

I'm surprised no forum contributors (so far) have any enlightening data that they can share.

[Old Dude]

Thanks AJ
I will see how this one goes and will try them if its no good

[marcusus]

All tyre manufacturers seem to recommend an increase of about 10% over the recommended cold pressure for high speed/high load/towing conditions. Do you really believe that car manufacturers deliberately recommend a pressure that makes the car doughy (and thus dangerous) just to make it "comfortable" to ride in and that they are colluding with tyre manufacturers in some sort of conspiracy to cause tyres to wear out earlier

Yes! I would hazard a guess that right comfort gets them more sales than a "minor" safety increase. You can't really gauge safety by driving a car (in fact you can only really gauge it if you have a crash), but comfort is very easy to gauge.

With regards to your DSC activating, it'll all depend on the algorithm Mazda uses to activate it in the computer programming, but there could be situations where it activates without needing to activate and vice versa. For example, if the algorithm specifically detects on the amount of verticle angle (aka camber) a wheel changes, then having a lower pressure will cause less camber because of the increased "grip" the two outer edges of the tyre will have. This doesn't necessarily mean that you actually have more grip, because the contact patch could possibly be much less based on how low the pressure is. Remember though, that this is only an example and quite possibly is not how Mazda does it. It just serves as an example to illustrate that even though lower pressures might not activate your DSC, it may not necessarily equate to more grip.

[Guran]

Tyre pressures affect so many aspects of a car that no one recommendation is going to suit everyone. In the grand scheme of things, most people rarely drive their cars beyond 5/10ths, let alone 8/10ths. The first sign of tyre squeal and they get all panicky! For the majority, they're more concerned about tyre wear life and ride comfort, not on limit grip and steering feel. That is why the recommended tyre pressures are so low - they favour ride comfort mostly and possibly tyre life (but only if you're pottering around), which suits 99.9% of kms dríven. If you drive beyond 5/10ths and want to experience the limits of the car without them being dulled by doughy tyres then it's best to up pressures beyond the placard recoomendations. You will get much less tyre roll in hard corners (hard cornered low pressure tyres don't grip too well if they roll off and the rims contact the road!), lighter steering, improved fuel economy, shorter stopping distances (especially in the wet), and better wear patterns. This is why the advanced driving schools recommend higher pressures: because they frequently drive and instruct thier students to experience driving well beyond 5/10ths.

As for the science, perhaps John Cadogan should look into this next time he does the tyre testing for Wheels magazine.

[JBT]

I'm surprised no forum contributors (so far) have any enlightening data that they can share.

Maybe I should have made that "enlightening factual data".

[Charlie Brown]

I’m coming in a bit late here. There's a lot of good informative comments, especially from Guran and others that are spot on.

I don’t subscribe to the theory that manufacturers put low inflation pressures on their plaques to make people buy their car because of a “better, softer” ride and I don’t subscribe to the theory that because 38psi works fine for PP2s on a Camry it must be OK to run PP2s on a MX5 at those pressures.

Vehicle weight - overall and front to rear, suspension design, roll centres etc., etc., will effect the pressures selected by the vehicle manufacturer to obtain maximum performance and ride.

Car manufactures don’t give a rats about tyre wear. The Bridgestone Turanza’s fitted to my wife’s Mazda6 were gone at 24,000 kilometres. The Mazda service manager said he’d seen them last just 12,000k so we did well.

Remember Tyre manufacturer will adjust their recommended pressure for the same vehicle depending on the height / width ratio of the tyre. So a 205x50 tyre might have a recommended pressure of 30psi and a 205x45 a pressure of 32psi when fitted to the same vehicle type.

When I ran PP1s on my NB I set the pressures at 31psi for the road and 37psi for the track. I did the same for the NC.

You can’t run 37psi in a MX5 on normal Australian roads with standard suspension and expect it to get through a rutted corner without skipping around. It’s too hard. The suspension can’t take an increase of almost 30% in pressure. Your tyre acts as the first absorption point in the suspension. Take that away and you mess up the manufactures’ design parameters.

Track conditions are different as stated by others above. On the track I get my first timers on road tyres to put in 36 or 37 psi to start. After that adjustment is by 0.5psi to change the balance of the car. NEVER let the pressures get above 41 hot as grip drops dramatically.

Back to the original query on PP2s or RE001s.

I fitted RE001s to the NC. Now with almost 3,000 kilometres up I can say that these tyres scare the hell out of me in the wet. Anything resembling a wet tarmac and it’s an excuse for them to spin up or slide under a normal sedate driving style. My old T-1Rs that were hard and down to within a mm or two of the indicator bars were far superior and I thought they were bad. I have yet to extend them in the dry. I probably should go to the Marulan Driver training track or find a quite back road with plenty of run off and test them out before passing a dry road comment.
Maybe they just don’t fit into the manufactures specs for the NC and should be avoided.

[JBT]

I fitted RE001s to the NC. Now with almost 3,000 kilometres up I can say that these tyres scare the hell out of me in the wet.

Hmmm....this seems to be a common complaint with the RE001 on many forums.

[bensale]

I fitted RE001s to the NC. Now with almost 3,000 kilometres up I can say that these tyres scare the hell out of me in the wet.

Hmmm....this seems to be a common complaint with the RE001 on many forums.

+1 Absolutly rubbsh in the wet... Very scarey! Coming out of any corner with even the slightest amount of throttle is pretty dicey... Although they seem ok into corners and under straight acceleration and brakes. I would not buy them due to there wet performance alone, if you're using them for track days good luck if it rains! Thankfully I live in melbourne and it never rains down here...

[Old Dude]

Hi guys a bit of factual info from the tyre companies this was copied from one of their web sites

Generally, the optimum inflation pressure is about 90% of the maximum level. For high-speed driving, drivers are recommended to use a higher than normal pressure.

If 40 psi is the general maximum as on most tyres, that equates to 36 psi as a general rule of thumb.

Obviously you need to set it at what works for you and your style of driving.

Old Dude

[JBT]

The Bridgestones on our NC are rated at 51 psi max and the C drives on the Astina at 50 psi. Don't think I'll ever be setting 45+ psi.

The Hankook website states "The optimum tyre inflation pressure is indicated on a vehicle placard" as well as "Generally, the optimum inflation pressure is about 90% of the maximum level. For high-speed driving, drivers are recommended to use a higher than normal pressure." They are mutually exclusive statements unless the placard pressure is about 90% of the max pressure.