Safe Speed Forums

In reality, that's pretty much indicative of the performance of modern tyres, rather than a particular endorsement of the car itself.

Granted the scooby will have pretty good brakes, but again "good" in this context usuall means a nice solid progressive feel to the pedal and little or no fade in repeated use from high speed, rather than achieving startlingly higher values of retardation.

The point remains that most modern cars with ABS and moderately decent tyres will still achieve braking performance way in excess of the expectations of their drivers, in "one off" emergency stops from normal speeds.

It would be interesting to see what the actual difference in grip is between a performance tyre and a "cooking" one...

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

I remember a tyre called Dunlop 'Elite' - a hard wearing high mileage tyre, with about as much grip as a cat on wet lino.

I'd be extremely interested in seeing how tyre performance has changed over the years. I wrote to a couple of tyre manufacturere a few years ago asking for data. I expected them to crow about their achievements, but I got nothing. Then I found a road test from the 30s or 40s indicating 1g retardation from the car in question. Hmm. Maybe tyres are just the same as they always were (Dunlop Elite excepted).

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

This is why Mercedes developed "Emergency Brake Assist". They did some research and found that a lot of drivers do not press the pedal hard enough in an emergency. The EBA system measures how quickly you move from the throttle to the brake and applies full-power braking if it believes you are in an emergency situation.

I fell foul of this "safety feature" in my Dad's E class on a 40mph dual carriageway. A gatso suddenly appeared from behind a tree . I wasn't speeding but I instictively moved my foot to the brake pedal and my eyes to the speedo. I barely touched the brake pedal but the EBA system banged on full-power braking, left skidmarks on the road and scared the living crap out of my passengers. It was fortunate that there weren't any cars behind me at the time.

There doesn't appear to be any way to turn off this dangerous (IMHO) system.

I agree, that it is tyres that matter - after all the only thing between the car and the road is the tyres, but suspension, shocks, set-up (camber, castor, toe-in), brake bias, assistance systems (ABS, EBD, Brake Assist,etc) all have a degree of effect. For example the Impreza Electronic Brakeforce Distribution will take the rear tyres to locking point giving more control at the front. The Mercedes Brake Assist was great fun until they fixed it beacuse, on the theory that most drivers don't push the pedal hard enough, they decided to give extra brake boost when sharp braking was detected - unfortunately tailgating autobahn drivers soon discovered that a sharp dab of the brakes turned into an unintentional emergency stop. Simba got in before me on this.

Tyre wear also has a dramatic effect - there are so many variables, that in order to know how your car is going to react at any time under hard braking, you do need to try it out.

The scooby in question was an enthusiasts car, and there are many discussions about which is the best tyre on ScoobyNet. The results include a degree of personal opinion, but the conclusion is that only a few types of tyre (such as Goodyear Eagle F1 GDS03 or Toyo T1-R) are up to the challenge of taking an Impreza around the track. Wrong tyres on the wrong surface and you go off - the same applies on the road. The two above are summer road tyres and are very good in both wet and dry, but very, very bad in snow and ice.

There are some tyre reviews out there - "Which" does some quite regularly (although they are only visible to subscribers) and apparently Wheels magazine did some tests too - not online, but referenced here http://www.aussiefrogs.com/forum/showthread.php?t=23777. The place for reviews if you don't mind it being about "tires" and not "tyres" is http://www.tirerack.com/, as despite being a retailer, they do comprehensive tests on their own track, and then use that data for recommendations - incidentally the best lateral G in dry cornering is 0.94g, but then car set-up comes into play. Perhaps you could contact them - the test data is online, but by sub-category and test.

There is no ideal tyre - many countries (but not the UK) encourage the use of Winter Tyres with different compounds and tread patterns for when temperatures are lower (not Snow tyres or Studded tyres which are completely different things). Perhaps if they were used more the entire country wouldn't grind to a halt the moment the first snowflake appears?

A famous motorcycle racer once said in reply to the question, "How do you do it?" after he had won his umpteenth race. "I do not use the brakes" he replied.
Seriously though, modern brakes are fantastic along with the tyres. My diesel Focus has now completed 90.000 km and disbelieving the inspection plug wear indicator for the rear drum brakes, I removed a drum and was amazed to see that the linings were not even half worn. And I drive quickly having raced and ridden motorcycles at high speeds (in South Africa and on the tracks) for many years. Always slow down by just lifting your foot off the accelerator pedal if you can only using the brakes to finally stop. But then a diesel-engined car has far superior engine braking performance, and for me, having driven them all, is far better for normal road use as long as you are happy cruising at 140 kph (87 mph) on the open road: along with the overall 48 mpg (6,10 l/100 km).

By the way, we live in Spain. With all the over regulation in the UK, I could not enjoy driving there anymore.

_________________
Brian Deller, author of the book, Motoring in Spain
www.spainvia.com

Hi and welcome BigBrian. Another ex-pat on the Costa Del Sol by the sounds of things? Not been there for many years but I remember plenty around that area, half the beach bars then seemed to be owned by ex-pats. Incidentally, the new points system there, is it a trial or is it for good?


Mmm, yes, the only good thing about my old turbo diesel Vauxhall, but other than that I have to say it was vile. A nice torquey petrol lump can be just as good, though the fuel bill for my VTEC'd Honda can be a bit and I've no idea what the thing is doing with all the oil it drinks.

_________________
Make everything as simple as possible, but not simpler - Einstein