How would sand bags impact a 560 SEL's self levelling suspension? Would I derive the benefit of added traction?

If I assume 46.2% weight on rear wheels with one driver in the car (car + driver: ~ 3440 lb), then I estimate there will be 47.7% weight on rear wheels after I put 100 lbs in the trunk.

Will I feel the improvement in traction caused by the weight distribution change: 46.2% on rear -> 47.7% on rear? It looks like a very small change.

Another separate question: Is it a good idea to put small sand bags around spare tire?

By the way, where can I purchase well dried sand and good bags at good price?

This looks like a reliable sand bag, but it is somewhat expensive.
http://shop.store.yahoo.com/stagelightswarehouse/25lbsandbag.html


Calculation detail is below.

Weight on rear wheels.
Assuming 3300 lbs curb weight, and 46% weight on rear wheels.
> 3300*0.46;

1518.00

x is the weight of sand bags I put in the trunk.
> x:=100;

x := 100

Percentage of weight on rear wheels after putting sandbags (%)
Driver's weight is assumed to be 140 lbs and be distributed evenly to front and rear wheels.
> (1518+70+x)/(3300+70.0*2+x)*100;

47.68361582



Increase in total car weight by putting sandbags. (%)
> (3300+70*2+x)/(3300.0+70*2)*100 - 100;

2.906976734



Increase in traction, which is assumed to be proportional to the weight on rear wheels. (%)
> (1518+70+x)/(1518+70)*100.0 - 100;

6.297229219







In conclusion, my car becomes 2.9% heavier, and has 6.3% more traction.