Using Different tire size than recommended
 

Hello- I purchased a used honda civic ex 2002 4dr. I recently noticed that the recommended tire size is 185/65R15, yet the car has 205/65R15 tires on it. Do I need to be concerned? Now I need one tire replaced. Should I get all replaced with the correct tire size or just replace one with the existing tire size?

You should be aware that the speedometer is off a little then. IDK much about tires so idk if you should be worried. IMO, you should replace with the stock tire size.

As both tires have the same aspect ratio (65) and rim diameter (15), I don't think the speedometer reading is affected.

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http://www.1010tires.com/TireSizeCalculator.asp

http://i75.photobucket.com/albums/i3...Picture1-2.jpg

You were right. Nice link.

yea i don't understand it though
i guess the keyword in aspect ratio is "ratio" and that the treadwidth alters what the aspect ratio actually means.

That's what I would guess as well.

dnt think you should b worried, they r just bigger tires lol

Sorry Ron, you are incorrect.

Whenever you change the width you change the height (diameter) of the tire. A 205/65 is 20mm wider and the sidewall is 13mm taller then a 185/65. So the increase in diameter is 26mm (1 inch)! This increased diameter slows down the spedometer and raises the
car higher off the ground. This usually affects handling and sometimes causes the tire to rub the suspension parts and/or body.

A quick lession in tire sizing...

The first # 185, 195, 205, etc. is the tire width in Millimeters (from bulge of the sidewall to the bulge on the other side not the tread width)
The 2nd # 35, 40, 45, 50, 55, 60, etc. is the aspect ratio (ratio of sidewall height to width) ex. 205/65 means the sidewall is 65% of the width (205)
R stands for radial and D or B stands for Bias ply (nowadays only trailer tires are bias ply)
The last # is rim size in inches

Load rating/index (the tires weight capacity at a given psi) and speed rating (the top speed for the sidewall) follows the rim size
87V, 91H, etc.

Speed ratings
Q - 100MPH (most snow tires are this)
S - 112MPH (most regular car (non performance) tires)
T - 118MPH (most non performance imports)
U - 124MPH only seen Goodyear make this speed rating
H - 129MPH Beginning of high performance tires
V - 149MPH softer tread compound, faster wearing, stiffer sidewall usually no mileage warranty*
Z - Above 149MPH (this used to be the highest speed rating) even softer tread compound and faster wearing usually little or no mileage warranty*
W - 168MPH really soft tread compound and usually no mileage warranty*
Y - 186MPH extremely soft tread compound and definitely no mileage warranty*
The above speedratings mean that the tires' sidewall was tested to withstand speeds at the max MPH for 15 minutes, and after that the tire has not been tested so it may or may not blow out.

*whether or not there is a mileage warranty usually depends on the retailer selling them, usually they will offer a defect warranty for some time in case the tire is defective like - radial pull, belt separation, etc. and some give warranty for treadlife, and it is YOUR responsibility to keep the PSI correct, do rotations on schedule, and wheel alignment checks if you want to get credit for new ones if they wear out (tread at the wear bars 2/32nds/inch)

The reason these performance tires usually do not have any mileage warranty is because the soft compound high grip rubber wears very fast, and add to that the driver is usually doing a lot of burnouts, running the wrong PSI, & out of spec alignment which wears them even faster. These tires have a low treadwear rating (ie less than 200,(UTQG)) see below for more info on treadwear.

Keep in mind that the rim width affects what size tire you can use on it: too wide a tire for a rim will make the tread area bow-out in the center which will wear the tread in the middle. too skinny a tire for the wheel will do the opposite (bow-in in the center causing the outer edges to wear).

The UTQG ratings.....

(U)niform
(T)ire
(Q)uality
(G)rading

All tires sold in the US are required by the DOT to have UTQG ratings

Treadwear - This number will tell you how long the tire will wear - The higher the number the more miles you can expect from the tire *
Traction - the tires' ability to stop on wet pavement (asphalt or concrete): AA - best A - good B- Fair C - Poor
Temperature - the tires' resistance to generating/dissipating heat A - runs cool B - runs warmer C - runs even warmer

Most performance tires are Traction A and Temperature A

* the treadwear rating is is only to be used when comparing one tire to another. This is best when comparing tires of the same brand, because different brands come up with this number differently. For example a tire graded 150 will technically wear one and a half times longer than a tire graded 100. there is no warranty to this effect expressed or implied from the manufacturer or the DOT by this rating

One general rule for treadwear is this - multiply the treadwear number by 100 (add two zeros) and then double it to get approximate mileage life
So a tire graded 200 is essentially a 40,000 mi tire (once again there is no expressed or implied warranty by this number)

THE MOST IMPORTANT THING TO REMEMBER IS ALWAYS CHECK THE PSI

TIRES LOSE 1 PSI per month and 1 PSI for every 10 degree drop in temperature so I usually add 4-6PSI in Nov. and by May they are back to pre-Nov PSI (since I live in the Midwest w/cold winters). Always check PSI at least once a month. Get a good gauge not a cheap one!

recommended (A) = 24.5"
your tires (B) = 25.5"

Once you've figured out the diameter it's just a matter of calculating the % difference; sure there are online calculators that will do it for you, but you might as well know the steps behind it.

(B-A/A)100
=4.1%

Typically +/- 3% is considered acceptable, a conservative number than manufacturers will tell you that you should aim for in order for your ABS, and cruise to operate effectively.

You speedo will be reading 4.1% slower than it was before. Speedos are often off by a little bit anyways. Use a gps to get a rough idea of how much, if any your speedo is off by.