I am running 15 X 6's up front and 15 X 7's in the rear and I am curious as to why I would run: 215-60 X 15 = 25.2 in 235-60 X 15 = 26.1 in vs 215-70 X 15 = 26.9 in 235-70 X 15 = 28 in Using the info in this thread: http://www.jalopyjournal.com/forum/showthread.php?t=74071 I used the chart to figure out the sizing here: http://www.buicks.net/shop/reference/tires.html Other than the overall height being less on the 60 series vs the 70...do I need to contend with the fact that I am running a wider rim in the back? I mean, will it look weird to use the same series tires front to rear if the width of the rims do not match up? Essentially I want to have blackwalls and avoid a low-profile look. Can I run the same size front to rear or will the rear be domed out? The car will be lowered 3 inches all around, with a bit of a rake towards the rear .25-.50 inch if that (taking into account if fronts and rears are the same over all height).
If your desire is to avoid the low-profile look for your tires, you will want to go with the 70 series tires over the 60 series. The series is a % of the sidewall compaired to the width. A 70 series tire sidewall height is 70 % of the tires tread width, a 60 series tire has a sidewall hight of 60% of the tires tread width. Generally speaking, a 215-60 series tire is wider and has a shorter sidewall then a 215-70 series tire would be and a 215-75 series tire would be taller and narrower then either the 70 series or the 60 series. The 215 designation would be the amount of weight the tire can carry at a given tire pressure. The bigger the number, the larger the overall size of the tire and the higher the load it will support at a given tire pressure. The "R" in the sidewall designation refers to it being of radial construction and the "14" or the "15" or what ever, is the rim diamiter size. There will probably not be a noticable difference between the same size tire mounted on a 6" wide rim compaired to one mounted on a 7" wide rim, unless they are standing side by side. On some cars, you probably would notice a pull if a 6" wide rim was on one side and a 7" wide rim was on the other side, but on some cars you might not notice any difference at all, and ceartianly wouldn't notice any difference between the 6" wide wheels on the front and the 7" wide wheel on the rear. Gene
60 series always have a low profile look, because they are. Stick to a 70 series on a wider tire and even a 75 series on a narrow tire to escape that dreaded "low profile look".
The 215 number is the tire section width in millimeters. So a 215/60 should be the same width as a 215/70, but shorter height. Being a hot rod (as opposed to kustom) guy, I like to see the rear tires a bit wider than the rim, and the fronts a bit narrower. On the back a 235 or wider on a 7" rim would look ok, up front a 215 would be better, or on a 6" rim a 195. Suggest you look at other cars and note the tires sizes, maybe ask what width the rims are if you can.
Squrrel's got it right - the first, three-digit number is the average section width of the tire in millimeters. I don't know what podunk auto mechanics course teaches that it has anything to do with load rating - maybe that's a tractor tire thing, Illinois-boy. Is the car finished yet? What size tires does it have on it now? Do they fill out the wheelwells? Does it rub when you lock over the steering? My personal opinion? I like 60-series rubber on the right car. It may not look bias-ply traditional, but that doesn't mean that it can't look cool. A good compromise might be 215/65HR15's. I ran these on a lowered truck, mounted on 15"x7" steel wheels, and they had a nice, high-performance look - like a stock car.
I have that tire/rim on the front of my stuff....it matches well with a 275/60 tire on an 8" wheel out back. As long as the tires are wide, the 60s series looks ok. On a more narrow rim, 70s would be the way to go. Overall tire height is really the key, 27"-28" usually fills up a wheel well on an older car.
The car has mismatched rims and tires on it right now. I think it is rolling on 15 inches with a 235 70 on the rear and it has 14 inchers with some cheapo temp tires up front. The rears look ok, but I want to get the rear down. Since I am using 3 inch blocks there is not much more I can do to get it lower more unless I do it at the tire. The body lines on the 54 Ford are weird. High front bumper, angled kick up in the rear and low center rockers. Looks lowered and raised at the same time. Guess I will have to cut off the rockers to get the look I need when I eventually c-notch the frame. I bought all new steelies and am trying to figure out a good look on this while I drive the kinks out of this newly built hulk of junk. Thanks guys for stripping the tire stupid from me. I have learned something new.
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