[Redpiston]

Showing ignorance here. When running staggered tire sizes, shouldn't 50's be on the front and 55's on the rear? I was looking at my tire sizes and mine are the opposite. I always thought the car sat high in the front, now I know why.

I was also looking at going from a 225 to a 215 to give me a little clearance from the rear well lip. However, they recommend a wheel width of 6 to 7.5. I haven't been able to measure mine yet, but they are 17-inch Crugers and I'm pretty sure they are 8 inch. Anyone ever put 215 tires on 8 inch rims?

[b-man]

On one of my cars I had 205/50-16 tires mounted on 8.5”’wide wheels.

Later changed to 205/55-15 tires on 7.75” wide wheels.

Pretty sure the max recommended wheel width for both was 7.5”.

You’ll be fine with 215 tires on 8” wheels if that’s what you want.

Recommend wheel widths are just that, you can deviate a bit if it suits your needs and it isn’t inherently unsafe.

[Redpiston]

Thanks B-man. Any advice on the 50s on the front and 55s on the back?

[b-man]

Well usually you want a slightly shorter and sometimes narrower tire up front when running staggered tires.

For example I have 215/65-15 front and 215/70-15 rear all on 6” wheels on my Le Mans convertible. So 25.9” tall front and 26.8” tall rear. Same section width just different aspect ratio.

Exactly what size tires and wheels are you using now ?

Perhaps post some pictures as well.

[Redpiston]

I have 17inch Cragars, I think they are 8 inch. Tires are 225/50s on rear and 225 /55 on front, which is backwards.

My passenger rear rubs the well lip when I make a turn. I thought if I went to a 215 the 3/8 narrower overall width might give me enough clearance.

[b-man]

Well going one size narrower if the rubbing is slight would probably solve it.

Of course you’ll want the same width up front.

I would get one mounted and check fit before committing to all 4 tires.

I think perhaps 215/55 all around (26.3” tall) so you don’t end up with something that looks too small and lost n the wheel openings. Also shorter rear tires will increase engine RPM in all the gears.

[SRGN]

The way it was explained to me years ago. First number is the section width in mm, second number is the aspect ratio, in percent for sidewall height. So on a 225/50, sidewall height is supposed to be 50% of 225mm, so it's supposed to work out as 112.5mm. An inch is 25.4mm, so it works out just under 4.5 inches. I prefer my taller sidewall tires in the back, just looks right to me.

[b-man]

Some sports cars come equipped with wider rear tires with a lower aspect ratio to match the narrower fronts in height.

An older example would be the 944 Porsche with 205/55-16 and 225/50-16 tires, mounted on 7 and 8 inch wheels respectively. So in this case the 55s in front and 50s in the back work out because of the difference in width.

Pretty much every high end sports car nowadays will have something like 30 or 35 series narrower front tires combined with wider 25 or 30 series rear tires.

[JLMounce]

As SRGN pointed out, the middle number is the aspect ratio and is simply a percentage of section width. As a result, it's possible and sometimes common to have a smaller aspect ratio tire in the rear. This typically happens if the tire in the rear is wider than the tire in the front.

In your case, the front tire is 11.25mm taller than the rear tire since both have the same section width.

Did you purchase these wheels and tires, or did you purchase the car with them already on it. From an aesthetics purpose, you're correct that this type of tire sizing you'd typically see the taller tire on the rear. You also note that you have rubbing issues in the rear. Is it possible the previous person that sourced these wheels and tires and done so with the intention of running the taller tire in the rear, but due to rubbing issues, swapped the wheels? Another possibility is than a tire rotation was done by somebody that didn't bother to look to see that there were staggered tire sizes.

What kind of car are these wheels on? A 225 section width tire on an 8" wheel is a bit narrow. I don't think it'd try to stretch a 215 on to an 8" wheel. That's a size more suited for a 6 or 7" wheel.

I'd pull a front and rear wheel off the car and look at the back of the spokes or the hoop. The wheel specs are often found there. You might find something like 17x8 0ET, which would be an 8" wide wheel with a 0 offset, or 4.5" backspace. Remember that wheel width is measured from the inside of the bead seats. An 8" wide wheel typically measured 9" from outside lip to outside lip.

Once you know what actual size and offset your wheels are, you can make some better informed choices. On many of these cars an 8" wheel with a 4.5" backspace has the wheel sitting too far to the outside of the car, and tire contact with the wheel well can happen. As widths get wider, you typically want to see something like a +4 to +8 offset to move the wheel inward. In depends on the car though and why measuring is important.

Have you considered cutting, or rolling the fenders if the rub is minor? That may also allow you to get the front wheel and tire on the back where it likely belongs.

[The Champ]

Originally Posted by Redpiston

Showing ignorance here. When running staggered tire sizes, shouldn't 50's be on the front and 55's on the rear? I was looking at my tire sizes and mine are the opposite. I always thought the car sat high in the front, now I know why.

I was also looking at going from a 225 to a 215 to give me a little clearance from the rear well lip. However, they recommend a wheel width of 6 to 7.5. I haven't been able to measure mine yet, but they are 17-inch Crugers and I'm pretty sure they are 8 inch. Anyone ever put 215 tires on 8 inch rims?

I've run staggered sizes on my GTO for over 20 years.

First set up was 235/60/15 (26.1") front and 255/60/15 rear (27").

Next was 215/55/17 (26.3") front and 245/50/17 rear (26.6").

Current setup is 215/55/17 (26.3') front and 235/55/17 (27.2") rear.

In all cases, the rears are taller and wider on the rear.

You don't say what kind of car is involved but it sounds like all 4 tires are 225's. A 225/50/17 is a short tire (25.9") and the 225/55/17 is a taller tire (26.7")

Personally, I prefer a taller tire on the rear so that the front end sits somewhat lower. If you are having clearance problems on the rear with only a 225 section width tire, your offset or backspacing on your wheels is most likely the problem.

[Redpiston]

Well I finally got some time to get a wheel off the car to check the back side for any information on the wheel as JLMounce suggested. Much to my surprise, the wheel appears to be 17x9 inch. I'm not sure if the 0 is for offset or if it is 9,0 for width of rim. It also appears to have a J.J. before the date. Don't know what that signifies. Photo attached.

So this opens up a whole new issue. It appears if I want to go to a narrower tire like a 215. Looks like I will need new rims to go with the tires.

These rims and tires are on my 1966 2+2 Convertible.

[b-man]

PM me your phone number if you’d like to discuss.

Talking with you is easier than typing a detailed response.

[JLMounce]

Originally Posted by Redpiston

Well I finally got some time to get a wheel off the car to check the back side for any information on the wheel as JLMounce suggested. Much to my surprise, the wheel appears to be 17x9 inch. I'm not sure if the 0 is for offset or if it is 9,0 for width of rim. It also appears to have a J.J. before the date. Don't know what that signifies. Photo attached.

So this opens up a whole new issue. It appears if I want to go to a narrower tire like a 215. Looks like I will need new rims to go with the tires.

These rims and tires are on my 1966 2+2 Convertible.

That's a 17x9" wheel. Doesn't appear that there is any offset information on the wheel itself. I'm actually surprised they were even able to get a 225 section width tire on there. It should probably be a 245 minimum.

I did some digging and it appears that the Crager SS in 17x9 is offered in either a 4.5" backspace which is a -13 offset, or a 5.5" backspace which is +12 offset.

If the wheel and tire package is rubbing the wheel lip, it's likely that you have the 4.5" backspace wheel version.

Here's what I would do personally. Through the wheel with the larger tire back on the rear of the car and measure how much space you have inboard before you start contacting the inner fender well. There's a 1" difference in backspace between these two wheels. If you have a minimum of 1.5" to spare inboard, I would sell two wheels and buy 2 wheels with the 5.5" BS. I would probably put a 245 of 255 section width tire on that wheel.

If there's no rubbing up front, simply put the wheels with the smaller tires up front.

If the 5.5" BS is too much and you'll start contacting the inner wheel well, but it leaves enough room to the fender lip, you can add a spacer as necessary to position the rear wheels were it needs to be. You can always add spacers to wheels with too much positive offset. There's nothing much you can do outside of fender modifications if the wheel has too much negative offset.