tire question

[Dan]

the tires on the front of my 2000 impala are firestone ( p225-60r-16 ) the tires on the back of the car are sumito ( 225-60r-16 ) and i found that the tires on the back are about 1/2 inch taller than the front . the tire numbers are the same just different brands so why is one brand taller than the other ?????

Topic

[Mike]

It’s all in the tread/covering design, the advertised size being based off the size of the tire structure. The simple answer is that tires made for good paved road/cornering performance and low noise will have a thinner overall amount of rubber on top of the structure making up the tread. Tires intended to sacrifice some of those characteristics in favor of having better traction in snow or off-road will have deeper/larger/taller tread blocks and therefore be a larger physical diameter than the road tire.

Tire design is vastly more complicated than that, but that is a simple general truth that answers your question (which is a good question, BTW). If you want to learn more or have other questions about tires, there is this long-standing tome of information on modern tires:
http://www.tirerack.com/about/techcenter.jsp

[Dave]

There are always differences between brands for all tires, that is why it is reccommended that all four tires be changed on all wheel drive vehicles.

Fopeano is a little misguided here, It isn’t the tires intended use but the manufacturer cutting costs where they can.

[Thomas Ferry]

You also forgot more weight in the front of the car then the rear too. That can also compress the tires as well.

[Dan]

I was told that the letter P in front of the tire size numbers also plays a roll in the height of the tire ???????????? another response sounded like their was some miss understanding about the tire’s . both brands are for car’s , both are all season thread touring tire’s I think maybe I should have said that neither brand is a winter snow tire . sorry for any confussion . one local tire shop by me said it didn’t matter the brand if the the numbers are the same than the tire’s are the same height and width . but of course I didn’t believe him that’s why I turned to the web site . I do thank everyone for the info

[Dave]

P – is for P-metric pretty much every car tire and most every truck through 1/2 ton

LT – is for light truck most everything from 3/4 ton to 1 ton dually.

But this is where it gets tricky because everything from S-10 pickups through a 1 ton is considered light truck. Everything from a F450 through a Tractor Trailer is medium duty, and anything bigger is heavy duty.

The size of the tire goes like this (P225-60R16)
225 is the tire width in millimeters
60 is a percentage of 225, so the sidewall height is 60% of the tire width
16 is the wheel diameter in inches

[Lorrin Barth]

To have an exact answer you’d have to be in charge of tooling at both tire plants.

[Author]

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