Re: newbie questions ... (snow tires, and octane number)

[Eliot Lim <eliot@lanmola.engr.washington.edu>]

> How important is it to change the tires? Does everyone change over to
> winter tires, or is it ok to keep the fat tires, and just drive *very*
> carefully? 

being very careful does not mean others will be.. it is always a good
idea to have enough reserves of grip available to deal with the
unexpected.  it also makes driving in snow *so* much more relaxing.  i
think the diminished anxiety level is well worth the price of snow
tires.

> My second question is about octane numbers. The car manual suggests that
> one should use 92 octane in the car. Now, I have always assumed that the
> reason car manufacturers insisted on higher octane gas was because of the
> "detergent" additives that were missing for lower octane gas (some years
> ago). So, what is the general opinion out there? For regular driving, do
> you really need high octane gas, or will 89 or 87 octane gas do?

the newer audi and vw engines all have very very high compression
ratios.  typically 10 or higher.  go compare that with say a chevy,
buick or honda.  the cars are meant to use high octane.  during the
60's cars with compression ratios this high had to burn 100 octane
or higher.  (hot rodders please correct me if i'm wrong)

my v8 has 10.6 to 1 compression.. the car is sensitive even to
variations in super unleaded fuel... if i have a bad tank it runs like
shit and gets poor mileage... once in a while i get a good tank and it
gets super mileage and runs wonderful..

eliot