Installed TD Wheels & Winter Tyres on the Europa

[saj 24]

Hi new on here. I have a lotus Europa S and just put winter tyres on the car yesterday.

Had to buy a set of TD wheels from TMS due to no winter tyres being available for the stock front wheels.

So the tyres I had put on were:

Front: Bridgestone Blizzak LM-30 195/55 R16 87H

Rear: ContiWinterContact T830P 225/45 R17 91H

I have a question about tyre pressures though, according to the tech data in the book we have the following:

Front: 175/55 R17 81W (CAD) 26 psi

Rear: 225/45 R17 90w (CFE) 30.5 psi

Now according to the book unladen weight, front 362kg (798lbs) and rear 633kg (1395lbs)

So how do I work out what my tyre pressure should be with the the difference in the load index. I'm assuming as the load index

on the new tyres is higher than stock that the pressures will be lower but what they should be exactly i'm not quite sure.

Is anyone able to help?

Cheers.

Saj

[Grumman 0]

Hello.... will be difficult to find a correct answer... last year changed to SE wheels/tires and then asked for correct tire pressure..But even dealers did/could not answer this q...So i stick with the original indicated tire pressure as for a normal S.... Maybe have a look at Opel speedster or VX info ?

rgds.

Edited December 16, 2010 by Grumman

[Bibs 11,156]

I run non-standard wheels on my Esprit and asked one of the more senior engineers at the factory what pressures he's recommend. His advice was...

"No clever formula I'mafraid, just basic testing. Beg borrow or steal a tyre pyrometer (athermocouple temperature readout with a needle probe) and measure thetemperature across the tread immediately after driving the car fast on smoothflowing rather than 90 degree corners. The temepratures should be within5-10 degreesC across the tread, ie. inside, centre and outside. If theoutsides are hotter than the centre then the pressure is too low, if the centreis hotter then the pressure is too high. Camber can also affect theresults, with more negative camber increasing the inside tread temeprature, butthis is fairly easy to seperate from the pressure effects. Once you havecorrect looking temepratures make small adjustents to find a pressure which givesthe front/rear balance and ride you want, less pressure generally equates tomore grip and a better ride and vice versa. When you wear out thetyres is it the centres or the side which go first? If it's the centresthen the pressures are probably too high, the sides and they're too low."

[saj 24]

Thanks guyz.

I guess i'll just have to play about with the pressures and see what happens.