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Are differing tire tread patterns dangerous?

edited November -1 in Repair and Maintenance
A simple question: I have four matching Continental ExtremeContact tires on my car. One now has a flat-spot due to a caliper lockup at speed and must be taken out of service. The spare is in good shape, but it's a Pirelli P4000 with a totally different tread pattern. Does that matter? Is there a safety concern? The tire is the same size and construction, just a different tread pattern and manufacturer.
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Comments

  • edited June 2008
    I don't know of any studies done on this topic, but personally I would buy another Continental ExtremeContact tire instead, or replace both tires on that axle with tires that are the same brand/size/tread pattern. I feel there would be a safety concern as the two tires will react to an emergency situation differently due to the different tread pattern.
  • edited June 2008
    I'll second Jad2007's advice.
  • edited June 2008
    The dangerous thing is having a tire on the back of your car lose traction while the front keeps gripping, which will cause your car to fishtail or even spin. This is why you want to but the tires with the best traction on the rear, but the trouble is that if you're comparing two different tread patterns you don't really know which one actually does have the best traction. Or one tread pattern may be better in one situation and the other one in another. Having all four of them matched in tire design and treadwear is the only way to get reasonably predictable handling.

    That said, on pavement during the summer it really shouldn't be that much of an issue. I wouldn't risk it in winter, though.
  • edited June 2008
    If you want to be as safe as possible, you want to match tyres.

    You did not tell us what car you have. If you have AWD or 4WD, it can cause damage to the car driving on tyres that don't have the same circumference. It does not take much difference so one or two tyres that have been worn and others that are new can cause some expensive damage.

    All cars can suffer additional handling problems under emergency conditions. That would be when you need to slam on the brakes or are trying to maneuver under poor conditions like high speed, rain or snow. If the best tyres are on the front, the rear tyres have a habit of loosing traction and swinging around so you end up looking where you have been and not where you are going. Not a good thing.
  • edited June 2008
    "Are differing tire tread patterns dangerous?"

    Probably not. No one here knows for sure.

    It might be possible to go out to the test track and create extreme conditions (heavy rain, high-speed turns) in which different tread patterns could affect the car's ability to manuever. Or maybe not. Since nobody here can give a knowledgeable thumbs-up to your intention they cannot endorse it, particularly since this is a safety issue. Hence the conservative approach to their responses.

    My guess? I've spent a lifetime driving with mismatched tires. I've never experienced a problem that could be associated with differing brands or treads. You will probably do just fine using the Pirelli.
  • edited June 2008
    zuper

    the AWD or FWD question needs an answer to get accurate info.
  • edited June 2008
    The car is a '94 Jaguar XJ6. Rear-wheel drive, with ABS. Tire sizes are identical, so I would think the diameter is too. I would think the ABS would compensate for differences in braking adhesion, if there is any, but maybe not. The Pirelli spare is relatively unworn; the Contis are about 3/4 gone, but they did just pass annual inspection, and I had hoped to get one more season out of them, because money is a little tight right now. But if it is a genuine safety issue, obviously I'm going to spend the money.
  • edited June 2008
    I'll third Jads' advice but add: Buy another matching Continental tire and keep the Pirelli as a s[are for emergency use only.

    Cappy makes a strong point. Accurate info on the AWD is needed.

    Check with a Jag dealer about the necessity of four matching tires due to the AWD system.
  • edited June 2008
    Mismatchng tread is only a minor concern. If they're on the front you MIGHT slightly feel a difference but still advised to match two per axle. My biggest concern here is the AGE of the spare. Rubber ages and deiving on a twelve year old spare, even with zero miles on it, can be asking for a blowout. Check the surface of your spare fo age cracks and replace it if it's too old.
  • edited June 2008
    There are some unknown variables here.

    Is the Pirelli rated the same in load rating, speed rating, and application (summer vs. all season, for example)?

    Is the vehicle AWD?

    Do you expect to drive the vehicle in bad weather with these 4 tires on it? How Bad? Snow & ice?
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