Tyre pressures are crucial on the LCR

[foxes]

I guess Nitrogen is more expensive scarcely available.

 

[Jonny]

I guess Nitrogen is more expensive scarcely available.

We make nitrogen in work! We use it for "capping" the boilers if we're off line for a couple of days, the accumilator pressure is only about 0.5 Bar though

We also buy it in by the pallet for purging the natural gas system... the price varies depending how quickly you need it delivered. I think it's about £1000 per pallet if you need it "same day"!! Don't think my tyres would take 150 Bar pressure though! lol

Anyway, back on topic!

As has been said many times before, the "book" pressure can only be used as a "guide". Not many people would spend upwards of £100 on an accurate pressure guage with 0.01psi tolerence and bother to send it back to the manufacturer for a service & calibration every year.

Most of us have a cheap a £20-30 gauge with massive tolerences from 0.5psi (one of the better ones) up to as much as 5psi (cheap 'pound shop' version). Some garage forecourt air stations can be as much as 10psi out

I know my £40 Michellin inflator is not reading correctly. I check my pressures at least once a fortnight and keep them at 33 - 34psi. However, after about 5k miles I've noticed the middle section of tread has worn more than the outer edges, so although according to my guage the pressure is right (or there abouts), my tyres are telling me they're over inflated...

 

[cuprablue]

......And, of course, being an expert you will also know that the 'guide' is written with the standard tyres in mind... not the many different aftermarket tyres that people may decide to run instead. Which means you will of course know that each tyre behaves differently and may need the pressure adjusted to be safe, perform as well or simply feel right.

.........

Very true. So much so that in fact it's the tyre manufacturers that you should be taking tyre pressure recommendations from not the car manufacturer for anything but the OEM fitment tyres. The car manufacturer has recommended tyre pressures for the OEM tyres taking in to consideration all of the characteristics of that tyre with regard to side wall stiffness, tread pattern/block stability, compound, total grip, carcas construction and materials etc etc in combination with the cars suspension, steering and chasis performance. A different tyre will have anything from similar to completely different characteristics in these areas and so will very likely require a totally different pressure to work at it's best on any given car.

cuprablue

 

[Jonny]

My old FR came with Continental Conti Sport 2 tyres from new whereas my mate had Bridgestone tyres on his FR from new, yet the book only states one tyre pressure for 225/45/17's.

I contacted Dunlop technical support a while ago to ask the difference between the SP Sport Maxx tyres in LCR fitment, as there are 3 Sport Maxx available in 225/40/18

92Y XL TL VW (SAP Code 517740)
88Y RHD MFS T1 (SAP Code 517073)
Z XL TL 1 (SAP Code 513456)

here's what they said...

The 92Y (SAP Code 517740) is specifically tuned around the chassis of VW Audi group high performance cars, and in some cases may be special order through a tyre shop.

The 88Y (SAP Code 517073) is not suitable for the LCR as it is not extra load. This tyre will shortly be phased out.

The Z (SAP Code 513456) is most likely what you'd have fitted if you went to a tyre fitter and asked for Sport Maxx. They are Extra Load, but they are "generic" as opposed to VAG specific.

So yes, some tyres are designed specifically for certain marques but are not necessarily OEM fitment.

I guess what you get on your car from new is whatever the manufacturer got the best deal on at the time

 

[NotApplicable]

One thing I have noticed is the tolerance to variation of PSI is greater on some tyres than others. I have Falken 452s on my Leon FR Tdi (150BHP), they like to be set to 33 psi on my digital pressure meter. One psi up or down and you can really feel it in the handling. The previous tyres - Bridgestone Potenza RE040 (standard fit) didn't mind being 2-3 psi out but just went a bit sludgy if they were low.

My advice would be to start at the "recommended" and see how it feels. After a day or so, move the pressures around and see if you can feel the difference. After a while you will be attuned to the car and will settle on the right pressure for your car, tyres, roads and driving style.

One thing to note, having higher pressures at the back than the front feels completely different from having lower at the back. Even if it is only by 1psi.

So far, Falken 452s rock! The same grip as any other tyre I've tried and a lot more consistent though hot, cold and wet!

 

[Skorchio]

Get your tyres filled with nitrogen rather than air too. Its particles are much larger, so your tyres don't go down as quick. It's alsomore stable. F1 technology!

Its not so they go down quicker its because as the tyres warm up the presure dont increase as much and u dont wear the center of ur tyre more..