PDA

View Full Version : tire guru, I got a question.



poorlilpoop
01-04-2006, 01:41 AM
225/55/15 should be the same size as 225/50/16, correct? Even the they are 15 and 16in rims, profile ratio should compensate it, correct? Or am I dreaming?

I got 225/50/16s but one of them got a flat tire. The tires that I want is not in stock right now, and it's going to take some time to get it. ( Goodyear Assurance TriplTred. They are all weather tires and they look promising.)
The spare that in the trunk is 225/55/15.

When I bought the 325is, it came with 16 alloy, which doesn't seems to be the stock wheels. The one in the trunk doesn't seem like the stock either. (It has mesh pattern alloy. They are both genuine bmw wheels. )

Anyway, if someone can shed some light, please do.

This the info I got from a tire caluator.

Tire 1 - 225/55R16
Tire 2 - 225/55R15

Section Width: 8.85 in 225 mm
Section Width: 8.85 in 225 mm

Rim Diameter: 16 in 406.4 mm
Rim Diameter: 15 in 381 mm

Rim Width Range: 6 - 8 in
Rim Width Range: 6 - 7.5 in

Overall Diameter: 25.74 in 653.79 mm
Overall Diameter: 24.74 in 628.39 mm

Sidewall Height: 4.87 in 123.69 mm
Sidewall Height: 4.87 in 123.69 mm

Radius: 12.87 in 326.89 mm
Radius: 12.37 in 314.19 mm

Circumference: 80.86 in 2053.8 mm
Circumference: 77.72 in 1974.0 mm

Revs per Mile: 808.0
Revs per Mile: 840.7

Actual Speed: 60 mph 100 km/h
Speedometer1: 62.4 mph 104. km/h

Speedometer Difference: - Speedometer Difference: 4.047% too fast
Diameter Difference: - Diameter Difference: 3.89%

The caluator said that I should not have diameter difference of more then 3.00% for safty reasons.
I tried many different tire calucators on the web, and this one has the greatest difference. Most of other calculators were very very close.

poorlilpoop
01-04-2006, 01:50 AM
Someone told me use this link as reference.

http://www.wheelsmaster.com/rt_specs.jsp

According to the link, the height is only off by .1in (3mm) So this shouldn't make much of difference, and I should be ok to use it for while. Since this is a daily driver I'll be easy on it.<!-- / message -->

Jim@tirerack
01-04-2006, 02:35 PM
You can use the 225/55R15 as a spare no problem. The amount of height difference between the tires will not matter.