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Dave B.
10-16-2006, 11:54 PM
First, please understand my question: I DO NOT DRAG RACE<

its more of a handling and looks issue,

QUESTION: "I have on the rear, a pair of 18 X 10.5's"

QUESTION: "I HAVE NOW A PAIR OF TOYO 295/35/18'S NOW"

QUESTION: "HOW DO I STAY ABOUT THE SAME WIDTH?? AS THE 295/35
BUT GAIN A LITTLE HIGHT ABOUT A 1/2 INCH OF SIDE WALL, A LITTLE TALLER TIRE FOR THE REAR END THAT WILL RAISE THE BACK END AND FILL IN THE REAR WHEEL WELL JUST A LITTLE? I WAS TOLD IT WOULD TAKE ABOUT A 305/35 OR A 315/30 KEEP IN MIND MY FRONTS DO NOT CHANGE, THEY ARE 275/35/18'S

Please, if your going to be kind enough to answer, please understand my question first, thanks all

Bartman01
10-17-2006, 01:50 AM
Figures based on some general calcs. Real tires mounted on real wheels vary based on tire, wheel width, and pressure. You will probably get closer numbers looking at the mfg tire specific data (they publish it on their web site).

305/35 will give you about 1/4 total inch taller wheel/tire over 295/35.
315/30 will give you about 1/2-3/4 total inch taller wheel/tire over 295/35.

Both will increase width more than they will increase total wheel/tire height.
295 = ~11.6"
305 = ~12"
315 = ~12.4"

Depending on tire, the 305/315 may rub against your suspension bolt.

Dave B.
10-17-2006, 01:57 AM
ok, Iv been looking on tire rack, If someone out there is running the
AFS 18X10.5's on the rear and has some wide ass tires on them, please tell me what to get?? I want the tallest and the widest I can get away with and Not use any spacers,,,,thanks

dewone
10-17-2006, 09:26 AM
Tire size calculator (http://www.miata.net/garage/tirecalc.html)
Try the above link just type in the tire sizes and it shows you about how much change you will get. Like stated before it will vary by manufacture.

ausie
12-01-2006, 07:48 AM
Dave, I understand what it is you want to do.... there are two ways to look at the issue. The first which was stated already was to go wider in width. A tire with a wider width having the same aspect ratio as a more narrow tire will be taller. The height of the side wall is a percentage of the tire width. The other option would be to find tires that have a higher aspect ratio. It would be more difficult to find taller tires say 295/40 or a 295/45.

Not sure if you would have problems with the ABS when having different diameter wheels in the rear than in the front. Taller wheels in the rear may cause a speed error to occur in the sensors when compared to the front speed sensors which may cause the ABS to pulsate the brakes when you come to a stop.

If you take notice that the 03/04 cobras have a nice spacing around the front tire but still seem a bit deep on the rear. It may be easier to drop the rear springs a bit or replace them with ones that will drop the rear by 1 inch or more so that the space between the fender and wheel would match that of the front.

The difference in space between the fender and wheel would give that optical illusion that the rear wheels are smaller than that of the fronts. The earlier cobras 99/01 with the stock stance made the rear wheel look small in comparisson to the front. The offset of the rear axles also helped to create that illusion as well as the wider fender flair in the rear compared to that in the front. This is not so bad with the 03/04 Cobras since they are a bit lower than the previous models.

With some styles of wheels, I have seen staggard fitments. 17" up front and 18" in the rear.