Tire pressures for upgraded elise

[FastSpider]

I know the standard pressures and I searched old postings but didn't find any recommendations on pressures for non-standard cars.

My S1 has standard wheels, with 185 at front and 225 at rear (on 7" rims) Pirellis (can't eaily buy Yoko LTS where I live).

I also have Lotus motorsport suspension, which is stiffer and lowered to about 110mm, and over 200 bhp, and weighs 1750 lbs.

I figure that I should run higher pressures than standard and I've been experimenting but have become confused. In some ways it feels better at 30/32 lbs, but the ride is too hard. At stock pressure it seems too soft.

I use the car a lot on the road, twisty ones... I also do autocross and track days.

So what is recommended for road use and track/autocross use?

If I get yoko 038's on 8" rims for track and autocross, what should I run them at?

Thanks for any advice.

[GreenV8S]

quote:I know the standard pressures and I searched old postings but didn't find any recommendations on pressures for non-standard cars.

My S1 has standard wheels, with 185 at front and 225 at rear (on 7" rims) Pirellis (can't eaily buy Yoko LTS where I live).

I also have Lotus motorsport suspension, which is stiffer and lowered to about 110mm, and over 200 bhp, and weighs 1750 lbs.

I figure that I should run higher pressures than standard and I've been experimenting but have become confused. In some ways it feels better at 30/32 lbs, but the ride is too hard. At stock pressure it seems too soft.

I use the car a lot on the road, twisty ones... I also do autocross and track days.

So what is recommended for road use and track/autocross use?

If I get yoko 038's on 8" rims for track and autocross, what should I run them at?

Thanks for any advice.

For a light car like yours, those tyre pressures sound awfully high.

Interested in non-Lotus comparisions? My TVR V8S weighs almost exactly a ton. It runs on 225/45 tyres. Suspension is lowered an inch and stiffened by a factor of three from standard (now roughly 300 lb/in at the wheel), power increased to roughly 285 bhp/ton.

As standard I ran it at around 24/26 psi on S02PP for road use. On hot track days I'd increase this a few PSI to reduce the heat into the tyres, on cold/wet sprints I'd drop it a couple of PSI. I have adjustable Nitrons which I have set moderately firm to match the springs but by no means harsh. With this setup, tyre pressure makes relatively little difference to ride quality, but I can feel the car getting more sloppy when I throw it about. I imagine that if I had the dampers a lot harder, they would deflect less and make the tyres deflect more. In that case, tyre pressure might make a bigger difference to ride quality.

Not sure where I'm going with this, except maybe to suggest if you're stiffening the dampers too far relative to the springs in order to make the car feel firmer, you might get symptoms like that. IMO the dampers should be as soft as possible while still controlling suspension rebound, and the chassis should be controlled primarily by the springs.

Does this help? Probably not!

Cheers,
Peter Humphries (and a green V8S)

[Gargamel]

i run 18psi frnt (185) and 26.5 rears (225)

i have a 111s and the low fronts keep understeer down to a minimum.

On the track I up the fronts to about 21 as I don't mind a liitle u/s on a circuit.

I guess on the stiffer suspension 20 frnt and 26 rear would be ok - but on track temps rise so ....

32 is way over the top ! might hit 35 36 on a t/d !

[Bombjack]

Gargamel - aren't you getting trouble with the sidewall folding under the rim with the front pressures that low? I have to admit I've been thinking about dropping the fronts a bit from their 26 psi normal (for an S2), to quell some irritating understeer. 18 psi seems a bit extreme though!

[FastSpider]

I also wonder if temperature matters? I'm in a hot dry climate, 70-90F is typical and it doesn't rain at all in the summer, then pours a lot for a few months in the winter. I did an autocross in the rain last March and it was excellent skidpan training

I'll try leaving the pressures at the stock level for a while to see if I get used to it. I have to raise the front suspension a bit, as lower pressures there seems to allow it to bounce down and bottom out more easily.

[Gargamel]

it's an S1 and I am fairly sure the book say 22psi
so 18 is a little low I agree - but no issues with the side wall so far.

[fastspider]

The book that came with my Elise S1 (one of the last built - originally a base spec car) says 23 lbs Front and 27.5 lbs rear for 225's. This is the same as 1.6 and 1.9 bar (but my US made pressure gauge doesn't know what a bar is...)

I'm trying 24.5F and 29R for a week or so to see how it feels.


>> Edited by FastSpider on Thursday 12th September 04:40

>> Edited by FastSpider on Thursday 12th September 04:42

[FastSpider]

So after weekend of fun driving, I guess I'm getting used to the softer tires, however some of the bumpier mountain roads (Bear Creek road in Los Gatos is a nice hillclimb plus wineries :-) I was bottoming out much more often than with harder tires. I'll have to raise the suspension a bit more to compensate....