Sweave textwidth

Hi,

How i can fix the sweave textwidth.

For example, in the chunk

<<>>=
MOTin <- 
as.numeric(iinquee$Q1)+as.numeric(iinquee$Q2)+as.numeric(iinquee$Q3)+as.numeric(iinquee$Q4)
@

In the output page some text is omitted, appear like this:

MOTin <- as.numeric(iinquee$Q1)+as.numeric(iinquee$Q2)+as.numeric(ii

+         as.numeric(iinquee$Q4)

I can change the tex file, but isn't what i want to do.

Thanks in the advance
Jorge M.