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.
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.
I’ll second Jad2007’s advice.
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.
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.
“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.
the AWD or FWD question needs an answer to get accurate info.
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.
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.
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.
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?
You might want to check the traction ratings on the sidewalls to compare. If you have antilock brakes, then that makes for less doubt. One other thing that is being overlooked here is that there is no guarantee that all four tires have the identical road surface condition at the same time. Your question is valid but there is no easy, simple answer.
I have mixed tire brands for years and have not had a problem. I have to ask: When did anyone ever hear of an accident traceable to mismatched tire brands? I have not heard it.
I have to ask: When did anyone ever hear of an accident traceable to mismatched tire brands? I have not heard it.
Neither have I, but I think it’s tough to prove mismatched tires as a reason for a crash. People “lose control” and crash every day and it’s not always entirely determinable as to what the exact cause was, but I’m not ready to take the slight chance that in an evasive/emergency manouver my car doesn’t react the way I expect it/need it to, causing a crash or worsening a crash.
It is more important to match tire size.
My 2 cars have different treads on the fronts vs. the rear since I bought the pairs at different times. Not because I’m cheap, just poor. I have never had a problem from this practice.
I don’t think anyone has argued against that setup, it’s when there’s different treads on the same axle that you might run into trouble in an extreme situation.
I buy in pairs, too, because I’m cheap… (and poor, by some standards!).
About 20 years ago - the early days of ABS - General Motors did a study where they put a worn, but an otherwise identical tire on a vehicle with ABS and then tested to see how the vehicle reacted when the ABS was activated. The result was that the car tended to pivot around the worn tire.
This reinforced the position that tires should at least be paired up on an axle. Before this study, it was common for some otherwise knowledgeable folks within the industry to argue that only driven axles needed to be paired up.
I’ve been looking for a copy of this study, but it’s possible that this was an internal study and never published - for obvious reasons.
For you guys that live in states that require annual vehicle inspections. Will this mis-match condition cause you to fail inspection?
Absolutely not. Even if you had a performance tire on one end of an axle and a snow tire on the other, you are in no danger of failing inspection. The written rules only insist on adequate tread depth on all four corners. The inspectors might note the oddity but they cannot make up their own rules.
[b] I would think the ABS would compensate for differences in braking adhesion, if there is any, but maybe not. [/b]
I think not. ABS really will not do much here, except when braking on slippery roads, like ice and snow.
While it would appear from your description the AWD 4WD issues are not applicable, but mismatching tyres front and rear can cause handing problems, under emergency conditions on dry roads, even with ABS.
I have never had a problem from this practice.
Most people will not. The only time you would normally have a problem is under emergency conditions, and in 40+ years of driving, I have only run into emergency conditions a few times.