Should I drink more water the day before a tough ride?
"More"  - more than what - if you are already an '8 litre a day' person, no it will not help. If you are like me (too much coffee, drink when I am thirsty), an extra couple of litres spread evenly over the day will be a good thing. 

Be careful not to over hydrate as it will change the balance of electrolytes in you system and could lead to problems such as cramping. A litre extra over a day won't be an issue, but more than that, use a proper electrolyte drink (Not the lolly water sold at supermarkets as 'sports' drinks - if it tastes good, its not electrolyte).  

Watch out for too much water causing you get up for the toilet all night and miss out much needed sleep. 

In summary - a little more than usual is probably good, too much more is not so good.