As the tyres are the car's sole point of contact with the road surface, it is important to carefully consider the different options available when the time comes to replace your car's existing tyres. If cost is your prime consideration (why did you buy a Subaru then ?), then the chances are that you will end up with a lower quality tyre, with some potentially undesirable side effects. As well as giving lower levels of grip, cheaper tyres may have unpredictable behaviour as they approach and exceed their limits, wear more quickly, and generate higher levels of road noise. This is not to say that all cheap tyres are bad, just that the old saying of "what you get is what you pay for" seems to be especially appropriate.
15 Inch Wheels
Unusually for Impreza parts, in the standard tyre size of 205/55 VR 15, there are very wide range of tyres available. There is simply not enough space in this FAQ to discuss them all in detail. Some owners have commented that the current Bridgestone Potenza RE71/RE-010 tyres are a bit on the hard side, and seem to be lasting remarkably well, given the punishment they receive. Most would prefer a slightly softer compound, which although would give a shorter tyre life, would result in increased grip and in both wet and dry conditions. Favourable reports have been given on both Pirelli and Yokohama rubber, although the latter may be a little too short-lived for all but the dedicated enthusiast.
16 Inch Wheels
For 16 inch wheels, the recommended tyre size is 205/50 VR (or ZR) 16. In this size, there are much fewer choices available, most of which tend to be at the performance (read expensive) end of the market. The same criticisms of the standard Bridgestone Potenzas will presumably apply in the 16 inch size, and at the time of writing, it is probably too soon for most '98 model owners to give feedback on alternative fitments. Tests carried out by UK and German magazines for similar sized tyres rated the Bridgestone S-02 the best overall tyre, having particularly good wet weather performance. Meanwhile the S-02 Pole Position is a softer compound variant which appears to give outstanding dry-weather grip too. The Goodyear Eagle F1, and Toyo T1-S have also had many favourable reviews by Impreza owners. Tyre performance is a very subjective issue, and tyres which suit some driver/car/environment combinations, may not be suited to others.
17 Inch Wheels
For those with 17 inch wheels, there is very little choice in the recommended tyre size of 205/45 ZR 17, in fact we only know of the Yokohama A520, the Pirelli P-Zero Asymmetrico and the Dunlop SP9000. There are, however, more choices available in the alternative size of 215/40 ZR 17 (including the highly rated Bridgestone S-02).
There has been some discussion on whether the higher rated ZR tyres are required for the Impreza Turbo. Subaru specify V rated tyres (for speeds up to 150mph - and acceleration and braking forces in line with a 150mph car) as standard, so you can be confident that the speed and load ratings will be sufficient for a standard car with normal use.
If you take your car on the track or drive hard on the road, Z rated tyres will offer better performance. If you have any kind of power upgrade, you may well take the potential maximum speed over 150mph, so you'd best fit some Zs.
There's a wider choice of sports tyres in Z, and if you've got 16 and especially 17 inch wheels, you'll have trouble finding a V to fit anyway.
Another popular topic for debate often revolves around tyre pressures. Drivers' experiences show that the Impreza is sensitive to minor differences in tyre pressures (you can easily feel a drop of 2psi), so it's worth checking them regularly. For the '96 model turbo, the recommended tyre pressures for the 205/55 VR 15 tyres are 33psi front, 32psi rear. Some dealers have suggested that these pressures are adhered to when fitting larger 16 and 17 inch wheels, however Prodrive suggest 33psi front / 30psi rear (up to 32psi on the rear for sustained high speed or heavy load) for all wheel sizes, while MRT suggested 35psi on both front and rear results in better grip and handling, at the slight expense of ride quality. Prodrive even suggest leaving the tyres at the pressures for trackday use, although increasing the pressure will stiffen the sidewalls somewhat. An owner in Milton Keynes (probably the highest roundabout density in the world!) reports that to combat excessive front tyre wear, Continental tyre engineers recommended that the MK police increase front pressures by 10-15%. The owner reports that while standard pressures wear the fronts in 8,000 miles, running at 36psi provides significant reduction in wear.
Another common query is whether the tyre pressures should be reduced for snow or cold and wet conditions. The answer to this is no. Better grip and feel are obtainable using the standard or slightly higher tyre pressures. On the subject of cold weather, it's worth checking the tyres if the car feels bad (more roll, poor turn-in) since when the air in the tyres cools, the pressure is reduced.
Expected Tyre Life
Not a topic that has cropped up frequently on the mailing lists and bulletin boards. An article in Performance Car magazine claimed that the fronts should last between 15-20,000 miles, with the rears being good for 40,000 miles. Some enthusiastic drivers have reported less than 12,000 miles for a set of tyres (track events are very hard on tyres), with some getting as few as 7,500 miles from a set. Some dealers have suggested swapping the front and rear tyres periodically at the 6 monthly services, to get even tyre wear all round. Doing this, would give an average tyre life of around 25,000 miles for a set of four. Obviously, when replacing tyres, you should ensure you get a matched set. Steve Breen experienced handling irregularities which turned out to be because one of the P Zeros was made in Italy whilst the others were made in the UK. (A reader tells us that Lotus issued a warning to Elise owners regarding mixing P Zeros from different factories due to the possible effects on the handling)
Common sense would also suggest that you always replace tyres in pairs (i.e. both at front, or both at rear), or that you replace all four tyres at the same time, regardless of how expensive it might be at the time. It would be better to spend a few hundred pounds on a matched set of quality tyres, than writing off your pride and joy as a result of a mis-handling car at high speed.
In fact, most Impreza owners seem to consider the need to replace all 4 tyres an excellent excuse to upgrade to a much nicer looking set of 16 or 17 inch alloys at the same time.
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