tyre pressures

[timber]

new member, new-to-me vRS July 05, 13,000 miles, silly q no1.

Pleased with car, turns in well, fast enough, good mpg.

When tyres are set to unladen presures in filler cap, car is v twitchy, needs constant correction. Temporary tweak, reduce fronts by 2psi. Poss better tweak, increase rears by 2psi.

But why/how do Skoda's produce an oversteery-ish fwd car with a heavy engine?

Or is there something wrong, toe-in, rear camber etc? Have Dunlop gauges for toe/caster/camber, camber measurements easy & accurate, others harder.

What next?

[Martyy]

correct me if im wrong anyone, but having lower tyre pressures on the front and harder on the back will make it oversteer, due to the heavier weight at the front and running softer tyres will mean the front end will grip more and at the same time having harder rears will make the rear of the car have less grip,and thus oversteer. usualy i have harder front tyres.

[ric04vrs]

new member, new-to-me vRS July 05, 13,000 miles, silly q no1.

Pleased with car, turns in well, fast enough, good mpg.

When tyres are set to unladen presures in filler cap, car is v twitchy, needs constant correction. Temporary tweak, reduce fronts by 2psi. Poss better tweak, increase rears by 2psi.

But why/how do Skoda's produce an oversteery-ish fwd car with a heavy engine?

Or is there something wrong, toe-in, rear camber etc? Have Dunlop gauges for toe/caster/camber, camber measurements easy & accurate, others harder.

What next?

what tyres are fitted and what condition are they ?

a lot of people on here run with slightly higher pressures than standard on the front , it helps with tyre wear and less tyre roll in corners

[mathepac]

correct me if im wrong anyone, but having lower tyre pressures on the front and harder on the back will make it oversteer, due to the heavier weight at the front and running softer tyres will mean the front end will grip more and at the same time having harder rears will make the rear of the car have less grip,and thus oversteer. usualy i have harder front tyres.

Makes sense to me; I'm used to having higher front pressures on fwd petrol cars; same front and rear on awd's.

But are Skoda's fuel flap pressures a bit on the high side anyway?

[timber]

Thanks guys

Tyres are Bridgestones, too late/cold to look for sure, but I think something like Aventura. They are OK; with a mileage of 13,000 and registered to a lady owner they would surely be the OE fitments.

I have always believed that increasing the pressure (within reason, say 10%) reduced a tyre's slip angle and vice versa, subject only to the tyres not skipping about on bumps.

However I have heard of sprint/hillclimb competitors reducing pressures for more grip; you would expect to do this in the wet. These guys spin up the driving wheels before starts to get a bit of temperature in them. Runs often take less than a minute and the rears might not warm up much at all on fwd.

Reducing the fronts by 2psi certainly worked for me on the vRS, but I'll put them all up by 2psi before my next long run as I don't like running softer than recommended.

Have I read a thread about rear camber kits? Not that I intend to tweak the car in any way. But increased negative rear camber would reduce rear tyre slip angles which is what I want - I think! Is there a topic search facility within the forum?

There was an interesting article about 4 years ago in Race Tech (fairly serious tech mag) suggesting that for racing purposes a better INITIAL response to small steering inputs would be achieved with a small amount of front wheel toe out. This was for both fwd and rwd cars.

As I said, the vRS turn-in seems excellent for a fwd hatch. If I have a criticism it is that the steering lacks feedback feel. Is this a function of the type of power steering?

[Wardy]

You may find that fitting Cupra spec bushes to the rear of the front wishbone, and Powerflex to the front will help with initial turn-in.

You may also find benefit in fitting a strut brace across the engine bay, between suspension turrets. How much difference this actually makes is a reasonably well discussed topic on here though

Steve

[timber]

Thanks Wardy. Envy you the Xenons, but could't find a car with them on. Standard lights pretty good tho. I'm not intending any mods, the car is mainly for my wife who loves it.

ric04vRS, owe you an apology, the tyres are 205/45 R16 Bridgestone Turanza's. At least I got the last 'a' right. Are the vRS suspension settings those for "Sports suspension" in Haynes manual? I notice the rear camber is specified as 1deg27min +/- 10min negative on all models - quite high. Wonder if my rears are within spec.

[ric04vrs]

VRS spec is sports spec suspension

Bridgestone Turanzas are cr@p and get worse the older and more worn they get IMHO

poor steering feel is one of the things that has been mentioned on all the road tests the mags did on the VRS , most likely down to the system used , a lot of other VAG products have the same issues

[timber]

Thanks ric04vrs. But surely they are equally cr@p at front & rear? I could try changing f to r and see if that improves feel on std pressures. But that would mean bedding tyres in for new positions, which wastes rubber. We tried another vRS on Michelins but did not drive far enough to show whether OK on them. They had a kerb protector, can't remember exact type, could have been Pilot Sport????