[A/S] Re: tow vehicle choice

["vrmanac" <andy@xxxxxxxxxxxxx>]

Hi Thomas

I would not be in a big rush to sell your 1992 Sub there is something 
you can do quite cost effectively that will inprove both handling and 
power.  When assessing a tow vehicle you not only have to think about 
the power output but also about how much power it will take to push 
the tow vehicle down the road.  In other words how much power will be 
left over to pull the trailer with.  

Your 4x4 Suburban's biggest power drain is the 245/75R x 16" tires 
that are on it.  What we do with them is change the tire to a 
Michelin 4X4 105H the size is a 235/70R x 16" Tire, the Michelin 
product number is 45271.  

This is a high performance tire that carries 44 PSI instead of the 35 
PSI that came standard on your truck.  It is the factory tire on a 
Range Rover.  It is a low rolling resistance tire rated for 105 MPH 
continuos use.  Not that you are going to travel that fast but what 
it means is that it is a high quality tire that has to disipate heat 
well and maintain balance, both of which are important factors when 
towing. The disadvantage is that they are more expensive and you can 
expect about 40,000 miles of tread life.

You likely have a 3.42:1 axle ratio in your Sub(if you look at the 
option codes on the sticker in your glove compartment it will be GU6) 
this tire will change it in effect to a 3.59:1 ratio.  This is where 
you will get the extra power combined with the reduction in rolling 
resistance you will get slightly better mileage as well.  The 
performance tire cassing has a far less sidewall roll than the 245 
tire which will improve your handling.  This is change that I have 
made to dozens of Suburbans and 1/2 ton pickups and the owners are 
always quite amazed at the improvement even when not towing.  The 
tire dealer will go a bit out of his mind when you tell him what you 
want to do saying things like the engine computer won't work and the 
anti-lock brakes won't work properly but this just does not happen 
the diamater will actually be the same as a 2wd with 15" wheels.  
Your speedometer will read 3 mph fast at 60 mph though.  Funny thing 
if you went to the same dealer and asked for bigger tires which would 
be detramental to handling and performance he wouldn't say a thing.


A 350 in a 3/4 ton will not perform as well as your half ton does 
since it has no more power, less attractive gear ratio's and more 
weight and rolling resistance.  A 454 will climb hills better but you 
will never save enough time on hills to make up for the time you will 
spend standing in gas stations.  The 350 is a more reliable engine 
than the 454 as well.

The other thing to look at from a handling perspective is your shock 
absorbers if they are weak they will accentuate the high centre of 
gravity in the Suburban.  Munroe Gas Magnum shocks work very well.  
With good shocks and tires your half ton will actually handle better 
than a 3/4 since the compliant suspension will work with the 
equalizing hitch not fight it.

There is nothing better you can do than put on a Hensley but your  
should be very stable with a conventional hitch set up and adjusted 
properly.  If I walk down a row of 100 units at an international I 
might find 5 that are really set perfectly and 50 I would be affraid 
to drive.  Make sure your ball mount is as close to the bumper as 
possible and that the Suburban is being pushed down on the front end 
(about 1/2") as far as the back when you hook up 

I hope this helps you out.

Andy