Tyre pressures - another stupid question

I know what they’re supposed to be and I can’t find the last thread on this so apologise in advance but…

What are recommended tyre pressures for A039’s for track use as last time I used them when I first bought the car I was getting excessive outside edge tyre wear on the fronts.

I’m on A048’s at the moment but going onto A039’s as have 3 trackdays coming up in Nov/Dec which involve a lot of motorway work aswell so won’t risk staying on the 48’s with the chance of the british weather giving me standing water and I can’t justify the cost of a spare set of wheels …unless anyone’s got some spare ones they want to lend me

Thanks again for indulging the new boy !!

I’m sure Uldis will provide his tire pressure thoughts.

However, there is also the roll bar you can play with. In theory I believe softening it will reduce understeer (the thought being you are rolling over on the to the edges) but the (in)famous Simon S believes the opposite works.

That said, on track I’ve even heard comments that going in harder makes it more neutral (although I’m not taking any responsibility if that goes wrong!)

In short, I think 30psi hot all round is in the right order (Pesky, wasn’t that what Gavin said?).


Ignore that, found an old post - http://www.exiges.com/ubbthreads/showflat.php?Cat=&Number=15106&page=14&view=collapsed&sb=5&o=&fpart=1


After some “playing around” with the pressures (for 48s)I find that 24psi all round when hot is good for me. I’ve kept the front ARB in the middle position too.

I suspect that similar pressures will be good with the 39s -I recall from a couple of years ago that Lord Whitter was running his car on track with those pressures & 39s.

I’ll give that a go. Cheers

Thanks all - I’ll run with Mr Pesky’s thoughts and report back after trackday on Monday.

The only thing now which I hate is I’ve just seen a forecast and there’s a chance it might be dry on Monday and Silverstone GP would I’m sure be better on A048’s !!!



If it is wet it can be a great benefit to put the antiroll bar onto it’s softest setting, inducing more roll and loading up the outside tyre, [color:“red”]they say !! [/color]

Ok then I’ve got to ask rather than nodding sagely and not having a clue in reality … how do I adjust the ARB and should a mechanical muppet like me really be fiddling with it ???

Pesky is right on (I told you… )
And the other thread mentioned can give you all details that have been (painfully) discussed in the past (sigh!, my discussions with Simon)

But one thing I don’t understand is, if you are on 48’s, why the fear and switch to 39’s?
What you will find is that the 39’s have a less progressive slide, about the same overall grip and yes, more ability to clear water, but I have found that the limit of the 48’s in about 1" of water is about 60 mph.
With the 39’s is about 65mph. Besides, they are more expensive.

I wouldn’t go back (ok, yes, if they were cheaper), and certainly not due to fear.

This from a chap that lives in Scotland and travels with (well used) 48’s to all track, near or far around the UK
(in fact, now for Oulton they’re close to be illegal and surely won’t be legal on the way back )


The thing is I have set of A039’s hung in the garage that have done 1 trackday and about 1000 miles on the rears and 2500 miles on the fronts of pure commuting road use by previous owner.

I took them off the car when I bought it and fitted the A048’s.

My “fear” is based on a couple of “interesting” moments I had with my S1 Elise when running A038’s which were appalling on motorways in anything like heavy rain and therefore I’m erring on the side of caution with A048’s.

In the damp of Mallory last weekend I was happy with the grip from the 48’s but then it’s so hard to compare as I haven’t driven on 39’s since July when I bought the car and did 1 trackday on them before swapping to the A048’s.

I’ve always driven performance cars of varying types, had numerous Driver Training sessions on airfields and circuits with Andrew Walsh at 1st Lotus so I’m not the slowest person round a track by a fair margin but have always erred on the side of caution of tyre choice for wet trackdays - am I just being over cautious with the A048’s ??

Advice please before I spend another �40 having the tyres swapped over only to regret it !!

Yep, IMHO you’re being over-cautious with the 48’s.

My opinion migh be biased because it’s always wet here in Scotland, and actually at the beginning I was dreading wet track days, but having done many in the wet with both tyres, I say I still prefer to leave on the 48’s, less hassle and I actually like their progressivity, even in the wet (the 39’s tend to skip sideways instead of sliding).

But then again, you also have the 39’s there, waiting.
What I would do is install the 39’s after the last trackday of the year, for the winter season. Does that make sense?


PS - remember, 24 psi hot.

Yeah it does make sense but I don’t use the car everyday and I’ve got a Beemer 330 for work trips and the runs to the airport so it’s basically a trackday toy - on that basis it would seem you’re suggesting leaving it on A048’s as I don’t stop doing trackdays just because it’s Winter - I’ve got 2 booked in December and 1 in January so far !!

Put on the 39’s for the snowy trackdays!

PS - are you doing Oulton on 12th Dec?

Can’t make Oulton on the 12th as heading for sunnier climes for Xmas & New Year.

What trackdays do you guys on here go to mostly ?

We’re getting a few more Exiges at SELOC days as more and more people realise how much better they are than S1 or S2 Elise (IMHO ofcourse !!) (4 or 5 out of the total of 40 odd Lotus’ at Mallory on Saturday were Exiges) but it would great to do a few different ones aswell.

Cheers again for the advice.


I have found that the limit of the 48’s in about 1" of water is about 60 mph. With the 39’s is about 65mph.

I don’t even want to think about how you worked that out Uldis! Ever considered being a test pilot??!!!

Hey David, Silverstone is probably one of the better places to be in the wet. It’s very wide and as those GP cars go so quick there’s lots of run off. When I was last there in the wet it taught me to drive very smoothly. If you can arrange it, it’s better to be wet in the morning as you’re much more likely to be caught out if it turns wet later! ‘Bridge’ is my favourite bend, possibly in the UK, a 95mph (in the dry!) right hander and then hard braking for the next left - fab!

If it is raining watch the last bend before the start/finish it gets VERY slippy. It looks quite quick but is really a 30mph touch. Enjoy!



The 48s are definately better than the 39s in the dry, & especially so when they get some heat in them. However, the 39s are a great performing tyre. If I were you, I’d put the 39s on during winter & do Nov to Mar trackdays (& road use) with them. Once they’re worn out - replace them with 48s!

ARB - I wouldn’t think about playing around with that until you feel you’ve reached the “limit” after experimenting with different pressures in the tyres. The main thing you will be wanting to eliminate is understeer, & personally I’ve found that running the 48s at 23-24psi hot, produces a nice balance. In saying that, I’m totally convinced that the car’s abilities will always be greater than my own, so unless it proves otherwise, I doubt I’ll try fiddling with the ARB (again!).

As mentioned earlier, Gav runs his race car with 28psi (hot) all round. I don’t like the feel of my car with those pressures, as it definately understeers (for me!). Gav obviously doesn’t have that problem - he drives so much quicker (particularly into corners) than the rest of us, plus his car is set up differently to our road cars!!!

So, step one is to play around with the tyre pressures, then if you’re still getting understeer, maybe step two is adjust the ARB. Oh, one other point, suspension geo is also important, so make sure that is set up okay - sorry can’t remember the “preferred” settings which are track biased over road settings (Gav did mine for me some months ago).


I can’t disagree with anyone here, and I can add that I haven’t tried 048’s so don’t know what they are like.

However, I run my 039’s at 23/26 and try to keep them around that when hot… which is kinda in the same area as the 24psi hot advice for the 048’s. I figure the idea is to keep the contact patch the same (hot and cold)??? why would it be different when hot?? unless sidewall flex becomes an issue??

Also i’d keep the 048s on your car until they are all used up instead of messin around swapping them if they are in perfectly good order. Also, i bet you WILL have lots of trouble with wheel balance after swapping, which is really why i wouldn’t change tyres that were perfectly good.

When they are done i’d put my 039’s on, by which time i’d have already played around with pressures and would have agood idea what works for me with a048’s… then id use that info as the starting point with the A039’s, play around some more untill I knew what was working for me then i might start messin with arb settings.

BTW moving the bolt out to the end of the arb will soften it.

so that’s my contribution…

Thanks for all the advice - have decided to keep the A048’s on the car until they wear out then decide what to do. After all they are standard fit from Lotus now on some cars and will be on S2 Exige.



Right On!