The Lotus Grand Tourers

One of the problems with modern tyres I reckon is that they are constructed to carry a 2 ton modern so their sidewalls are far too stiff (stops them over-heating /degrading) for a 1.1 ton Excel and need a lot of inflation pressure so any enhanced grip over yesterdays OEM Excel tyres is likely down to the modern compound - unlike a modern, the Excel doesn't need stiff side walls to make the steering responsive ...it has brilliant steering designed-in via geo..

What I like about the Potenzas is their rounder shoulder but time will tell - the Toyos T1rs were good when new ( due to siliconised modern compound) to begin with but the shoulders universally wore badly on all tyres leaving the centres with loadsa tread -despite increasing pressure to a silly 30 psi to get the centres worn. I know the T1Rs have stiffer , squarer, sidewalls as a feature - that's one of the documented differences over the superseded T1Ss.

Contrast that with Avon CR500's specifically built for 500 kg Caterhams - I have some on the Clan. you can run low pressures and they grip massively on the soft compound (wear rate 20 versus more like 200 on a normal tyre) at pressures 16 psi front 20 psi rear - but they still last a long time on the lighter cars.

Martin, I have a brand new set of 2tires for £75 + shipping. If you are interested I could have a look for the shipping costs.

Guys, Many thanks for the feedback on these. Lotus spent a lot of effort to give the Excel good 'road feedback' and I am keen to preserve this quality. I'm pleased to hear that these tyres don't diminish this. Once I have my alloys refurbished I shall go for a set of the 205/50R15 RE002's then.
Martin.

ive got these tyres on mine. all 4 changed at same time. as they are narrower than standard 215, what is the best pressure do you think?

Tyre pressure to get best contact patch can be influenced by width - but also the carcass construction & kerb weight /loading too may dictate a minimum operating pressure per se. If the carcass is particularly stiff then you might need higher pressures just to prevent too much sidewall distortion/ shoulder tread deterioration as low pressures may give less support to the sidewall.

I haven't driven my Potenzas in all operating conditions to know what's best - so when the Excel is back on the road this summer I intend to take a IR temp gun on trips to measure tread and sidewall temps to be sure they don't overheat on too low a pressure - I'll start with 26 psi and go 2 psi either way to see what's what.

I have had them on 2bar... There is a little piece of autobahn on my labour GP