Yep LTS 048 fronts are super Hard compared to the rears. IMO this was Lotus’s way of ‘building in’ some safety understeer. I bet you find a set of fronts lasts three sets of rears? I know mine did. The ‘M’ compound 048’s are miles better and give loads more front end bite. 888’s give a more balanced setup to LTS’s too IMO.
Geo obviously makes loads of difference too as do damper settings.
Apologies if it’s been mentioned before as I skim read most of the thread after the OP.
It sounds like you are only getting understeer on the lower speed tighter bends, primarily on initial turn in, mid corner and exits sounds okay, as does the higher speed bends.
You mentioned that the ARB was on it’s softest setting, if the symptoms are as I mention then I’d try stiffening up the bar a touch.
You may lose a little of the higher speed turn in and mid bend understeer may increase slightly but if it’s as good currently as you mention you can probably get away with losing a touch without any big effect. It will mean that the lower speed turn-in should improve.
The thing that confused me was it started off great for 3 or 4 sessions of 20 minutes, then just started to under steer and got progressively worse after that to the point i was going diagonally. 
Slow in was proving faster once this started but i didn’t feel the speed at which it started to under steer was excessive. I know there are some great tips posted here to drive round it, i am also trying to understand what was the cause and why it got progressively worse.
hi,
i would have also come the conclusion as you and think it must be the tyres as all else was fixed…ok, fuel levels and your entry speed may of made a change…but, it does sound like tyres…
on a dry track day at knocky, i noticed after about 15 20 laps in the tyres started to show small signs of understeer here and there…so much so at the chicane i entered a bit quicker than normal and found understeer…so, much so that i didnt think i was going to make it, so ended up cutting across rally style…
when i was in the pits i noticed that the tyres were graining quite a bit…
i have the 340r set up on my exige and found it better than the original… as i noticed that the graining was only on the shoulder of the tire when on the original settings so decided to go for the 340r setting to see if this improved. as the graining was now more across the tyre i figured that this was a good sign? the train of thought was that i was now getting a better contact and working t tyre better…but im no expert!
i expect that this is the journey all track day and race drivers experience for the first time and it becomes part of the skill and knowledge of being a race driver undestanding it all…
anyway, i would say, experiment a little and start with a nice geo and then maybe look at some nice fresh rubber…slicks, sound good lol…
leigh
P.S. oh forgot to mention tyres are toyo 888’s GG compound