Increase tire pressure when towing?

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May 25, 2022 | 03:57 AM

vtraudt

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From: Brighton, MI

Increase tire pressure when towing?

The door label typically provides tire pressure for 2 load scenarios (half and full).
Should the tire pressure increased (rear?) when adding 700 lb tongue weight?

May 25, 2022 | 04:45 AM

B6-3.0L

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Quote:

Originally Posted by vtraudt

The door label typically provides tire pressure for 2 load scenarios (half and full).
Should the tire pressure increased (rear?) when adding 700 lb tongue weight?

It’s not a bad idea to increase the pressure. I’d do all four (i.e., extra load on front tires when braking). A tire’s max load capacity is measured by the manufacturer at full max air pressure.

A 700lb tongue weight is a bit above factory tow package limit of 660lbs (550lbs for aftermarket). You may want to consider doing some weight shifting backwards on the trailer if possible. Otherwise the steering may be a bit squirmy.

May 25, 2022 | 06:13 AM

vtraudt

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From: Brighton, MI

yes, I don't use 700 lbs , just throwing a number (my Treg actually does a bit more than the Q7, 3500kg - 7716 lb with theoretically 770 lb tonque (btw: europe max is 150 kg or 300 lb).
And yes, that '10% of tow weight' dates back from towing with tractors (ahem: pick up truck) with solid axles, tall wobbly tires, leave springs, etc. and also resulted in the 'patch' of having to use weight distribution hitches (since the front wheel lost contact and could not control sway anymore).
Last time I loaded the trailer (nominal 7000 lb max, I figure 5400 actual mainly due to 40 gal of fresh water), I had 420 lbs on the tongque scales, super stable (Treg with air suspension; 295/35x21 Q7 wheels/tires).
But tires (Michelin) have only 51 psi max rating, so not much room to increase (say 39 front, 45 rear on door label). Currently: 43 and 48 (front also higher for braking, but also using weight distribution hitch).

May 26, 2022 | 06:37 PM

'10Q7TDI_Prestige'

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From: USA - NM

The inflation pressure sticker is relevant/developed for the OE tires the car came equipped with. It does not account for variances in tire types, newer tire tech, different sizes, etc. Many times you can go online to a tire retailer site and it will show you the minimum inflation pressure to achieve load rating on the tire, as well as max pressure for the tire, or you can get max off the sidewall, etc.

Depending on the tire, there can be a big gap between achieving load rating vs hitting max tire pressure. Several of the forum members here use significantly lower pressures for an unloaded car / general use, then pump up for extra support when towing or with a fully loaded vehicle, etc. The amount of leeway you have in inflation pressure depends on your driving style and the actual tires type and size you put on the car. All tires are not created as equals...they just have to able to meet the load rating for this vehicle.