Ulitimate Fixie coming soon. Guy Martin Speed

We were advised that stabilty is key issue on these things so much so talking to Dave Legrys (who's done 110mph) he was going to advise against Guy riding a bike with road wheels. We actually end up running 1.95" tyres with slight tread, Aero postion not an issue behind a fairing, Comfort/trust is, I built this for speeds of up to 130mph I thought giving Guy a stable bike was paramount.
Wouldn't a longer wheelbase / longer trail give you more stability?

What impact would the width or the tread of your tyres have?