PhiDeltBee

iTrader: (1)

I'm pretty sure it will, just wanted to clarify.

mrohno

iTrader: (1)

Should be fine.

flowrider

iTrader: (9)

According to the tire manufacturer's, a 275mm cross section tire will fit on the 9" wide rear wheel of the F. Some members have put 245/35/19 on the front and 275/30/19 on the back. A 265/35/19 would be a bit too tall, and a 265/30/19 would be a bit too short. When I retire I will be putting a 245/35/19 on the front and a 285/30/19 on the back. A 285 is technically too wide for the rear wheel, I feel quite sure it will work without issue. The 245/35 and 285/30 are both the same height, and the correct height for the F.

Lou

UCrazyKid

275's fit, go with them.

245/35/19 front
275/30/19 rear

No issues.

PhiDeltBee

iTrader: (1)

Thanks guys. 255 is just too narrow for 416HP.

bnizzle87

im due for new tires as well. id like to mount 275/30 or even 285/30 in the rears. will the fenders need to be shaved. im sticking with the OE wheels with Tein CST coilovers. many have requested that 245/35 would fit nicely in the front, so im just a little worried about rubbing in the rear.

Ajs1

Im a bit confused...If the F comes from the factory with a 40 series 19 front and 35 series 19 rear, how can a 35 front and a 30 rear be the same height on a 19 inch wheel?

PhiDeltBee

iTrader: (1)

The 35 or 30 is only an aspect ratio, not a true height in millimeters. There's a formula involving the tire width that give you the aspect ratio.

This number tells you the height of the tire, from the bead to the top of the tread. This is described as a percentage of the tire width. In our example, the aspect ratio is 75, so the tire's height is 75 percent of its width, or 176.25 mm ( .75 x 235 = 176.25 mm, or 6.94 in). The smaller the aspect ratio, the wider the tire in relation to its height.



Two tires with different aspect ratios but the same overall diameter High performance tires usually have a lower aspect ratio than other tires. This is because tires with a lower aspect ratio provide better lateral stability. When a car goes around a turn lateral forces are generated and the tire must resist these forces. Tires with a lower profile have shorter, stiffer sidewalls so they resist cornering forces better.

Ajs1

Thanks for the clear up!

PhiDeltBee

iTrader: (1)

You bet! I went through all of this when I put new wheels and tires on my BMW.

lobuxracer

iTrader: (2)

The easy way to figure this out is to look at the spec sheets for the tires. Tire Rack lists a revolutions per mile number. Find the OEM size and look at the revs per mile. Find all other tires with the same (or close) revs per mile and you've found tires with the same diameter.

If you look up the OEM tires, you'll see they're 797 for the front and 799 for the rears. Tires with the same revs per mile are 295/30/19 (none of the 275 or 285 tires match the OEM spec). There is no exact equivalent for the front.

The rule of thumb is, if the tire is within 2%, it's an acceptable substitute. Just remember, if it's 2% smaller in diameter (more revs per mile) your odometer will spin up just that much faster. So your 275/30/19 is going to put your car into high mileage quicker than a 295/30/19.

There are lots of games you can play with this if you're not too picky about performance. If you ARE picky about performance, the options are pretty limited.

Joe Z

iTrader: (10)

Here is a handy calculator....

http://www.miata.net/garage/tirecalcold.html


Joe Z

flowrider

iTrader: (9)

You're right of course, but we must also look at tire wear. If we look at the PS2 in the sizes mentioned for the rear:

The 255/35 has an OD of 26.0"
The 285/30 has an OD of 25.8"
The 295/30 has an OD of 26.0"

All the tires mentioned above have a tread depth of 9/32" (or 0.3") Therefore the 295 or 255 tires listed above tire would wear down to the OD of the 285 tire before wearout. IMHO, close enough so that the speedometer really wont notice.

Lou

lobuxracer

iTrader: (2)

The speedometer doesn't affect resale. The odometer does. While the 285 is only going to add 0.8 miles per hundred miles traveled initially, as the tire wears down it will be farther off. The OEMs are held to tight standards for odometers, but not speedometers. Honda got badly beat up for inaccurate odometers at one point.

So, regardless of wear, the smaller diameter tire will show higher mileage for the same distance traveled. If resale is important to you, it would be wise to know this before slapping on a set of tires in an alternate size. Again, 2% is considered fair enough and a 285/30 is well within 1%, so it's not unreasonable to run a 285. If you have enough rim, you'd definitely be better off with the 295 for the long run.

Galaxy 40

Is the width of the wheel also a factor? I tried the tire calculator and did not see an inputs for wheel width. (don't tires stretch on wider rims giving it a lower tire sidewall.Right or wrong?) What If I have a 19x10 for the rear and use a 285/30 won't that have a smaller OD as to a 19x9 on a 285/30? Any formula for this?

Also what would a 285 sidewall look on a 19x10 rim?
Straight?
Slanted?(stretched)
chunky?(due to too much rubber)

Thanks