computer economy chip

I doubt it, but the good news is you can get pretty much the same result by increasing tire pressure to 10% below the max pressure listed on the sidewalls, and accelerating gently. Also, don't run the A/C while getting up to speed or climbing hills. Those changes should be good for about 3-4mpg more, which is the most you could expect from a chip...

Not that I'm aware of, I've never seen a chip for an older Volvo, and chips tend to be to improve economy.

A 960 is a really sweet ride, if you want economy, I'm sure you can find someone to trade you a nice 940 for it, or if you can find a 740 with a manual gearbox that will get you into the high 20s highway. 940 Turbo has decent performance and still can manage 24 highway which is better than the 960. All US 900 series are automatic which costs you several mpg.

... but don't brake or corner too hard in the wet!

and accelerating gently. Also, don't run the

If you are running good (not even great, just "good") tires it won't be a problem. If it seems a little too stiff, back off the pressure one or two psi at a time.

I have Goodyear F1 on the back of my 940 and had the pressure up at

+8psi for a long trip 80% loaded. After finishing the trip and going back to normal loads I didn't reduce the pressure for a few days, the back end does breakaway in the wet and you do lose grip, it is simple physics, the economy goes up because the contact patch with the road is reduced, you will end up wearing your tyres in the middle and have less chance at avoiding unexpected obstacles. Not worth the risk IMO.

If you want economy this way then much better to fit the skinniest tyres (correctly inflated) that will go on the rim, and you benefit from reduced air resistance as well as rolling resistance.

Of course making sure the tyres are not under-inflated is important too.

-- Tony

It's not quite that simple. The rolling resistance can be reduced without reducing the size of the contact patch, by making the tire stiffer - i.e. by increasing the pressure 10%. What is the Goodyear F1? If it's a Summer tire that could well make it slippery - I wouldn't use Summer tires for anything except racing on dry pavement. A good all-season, with somewhat stickier rubber, should be fine running 38psi.

Postscript: I just looked, and the F1 is indeed a Summer radial.

With the greatest disrespect, not being a snow-tyre has nothing to do with rain performance. If Summer tyres weren't able to deal with rain, they'd be completely useless - and have absolutely no market.

Wrong definition, wrong application to the situation in question. In short, you're wrong.

that could well make it slippery - I

All-Season tires have a more open tread design than Summer tires, and this helps in rain. Summer tires aren't "useless" in rain, I just prefer the all-around traction of All-Seasons to the mainly-dry-pavement traction of performance Summer tires.

Summer = rain tyres All-season = snow tyres

You're reading too much into the names.

The names and specs are also geographical, In N.Ireland we have rain pretty much all year round, varying from slight to downpour at any time. Snow is rare, and ice normally abated with salt.

We have only one type of tyre, no such thing as a summer tyre here, and I'd day that a F1 here is pretty soft, and has pretty open tread. In mid europe they have much harsher climates with hotter summer and colder winters, I guess the US is similar. They have to change tyres because of how the temperatures affect the rubber, not really to do with whether there is snow or ice on the roads. Of course they do try to optimise tread patterns more for typical weathers, but it doesn't make that much difference.

Any advice about pressures is therefore at least geographical and seasonal, and probably car and tyre related to. Unless you are an Engineer and able to experiment I would just follow the manufacturers advice.

-- Tony

Good point about geographical differences, but I have to disagree on two points: you don't have to be an engineer to experiment with tire pressures - just don't exceed the maximum or minimum rated pressures. And the difference between Summer and Winter tires here *is* about grip, not about how the seasons affect the rubber, except that soft compound snow tires don't hold up well in Summer heat.

I am sure grip is a major function but I am not sure if cracking or bursting might be a problems aswell.

I can't say I know directly for sure, but Engineers I speak with in mainland Europe tell me the rubber in winder tyres is too soft for summer use, and summer tyres become too hard in winter. The rubber doesn't flex properly or does not provide enough stiffness, and the wrong tyres becomes dangerous when used in the wrong temperature even if the road is dry.

-- Tony