Is it possible (or even wise) to drop rim size to save money on the tires?

Question

My girlfriend bought a new car recently and got a flat. turns out the model she bought had 15" rims, and the tires are incredibly hard to find and expensive. 14" rims are standard on the car and you can find much cheaper tires easier with that size.

Is it possible to drop down to the smaller rim size?

Answer 1

also bear in mind smaller tires have a smaller circumference,so you will need higher revs to travel at the same speed for 15" tires,higher revs =higher fuel comsumption,could increase by 10%

Answer 2

NO! This may not be a sensible thing to do at all.

I'm going to take a wild guess and say the car in question is a Mazda Protege because this comes up all the time with this particular car. Mazda does an amazing job of putting rare, unique and expensive tire sizes on even its economy models. Many owners are not prepared for this. Even if it isn't a Protege the example is still useful;

A base model Protege from a few years ago has a tire size of P185/65R14 85S. The P means a P-Metric sized tire, the 185 is the section width (NOT tread width) in millimeters, the 65 is the aspect ratio, or height of the sidewall represented as a percentage of the section width, R means Radial construction and 14 is the diameter of the wheel the tire goes on in inches. 85 is the service rating and gives the tires load carrying capacity. S is the "Speed" rating which indicates the level of performance the tire is designed for.

Like I said, P185/65R14 is the tire for the basic model. The fancy ones come with a P195/55R15 84V. Obviously this is a 15-inch verses a 14" tire but the differences don't end there. This tire is also wider which presents a wider footprint on the road. This enhances dry weather handling and braking. The shorter sidewall wil also impact handling and braking because of its reduced flex over the 14-inch tire. The performance rating of V is also much higher than the S of the standard model car. This means the construction of the tire is considerably more sophisticated than that of the 14-inch tire which again impacts handling and braking.

All of these characteristics are taken into account when the engineers design the suspension and braking systems on the car. Cars built for the 14-inch tire are not engineered the same as those that take 15-inch tires because each tire has different performance characteristics. In other words, if you change to a smaller tire with reduced specification over that originally fitted, you stand a chance of negatively impacting how the car stops and turns. You are essentially re-engineering the car, and I'm guessing you don't have a degree in automotive engineering. Since this impacts the SAFETY of the vehicles operation, any tire store that would be willing to perform this modification for you is not a tire store I would want to do business with.

At my tire store we pride ourselves on being professional and knowledgeable. What you are proposing is not something we would do. I would rather lose a sure sale then to do something that has a negative impact on vehicle performance and safety, just so the customer can get cheap about the #1 safety item on the car!

Or short version... Tires are the last thing on the car you want to get cheap about. They are the most important thing that keeps you from smashing in to stuff. Stick with what the people who built the car recommend.

Answer 3

The OEM size on that car was 205/55/16. 225/50 is a popular size to run because it is almost the exact same diameter as the OEM size. If you run a 40 series, not only will your speedometer be off by quite a bit but you will be adding mileage to the car at a faster rate than you are actually driving. Another thing to consider is if you get a flat, the spare will be bigger than the rest of the tires and your diffs may burn up if you drive on it for more than a 1/2 mile or so like that. even at lower speeds. I would stick to the 225's or go back to the 205's. Lower profile will also make the huge front wheel well look even bigger. As far as a good size for the track, I would run a 17X8.5 with a 48mm offset and a 245/45 tire. That's about the widest that will clear without fender modifications and still be very grippy.

Answer 4

You are not going to save enough money on tires to justify the cost of the new rims. Sometimes you can move up or down one size on your tires, though, and save some money. If she has a 195/70/15, she could go to a 205/65/15, or something like that. Ask them at the tire shop what other sizes you may be able to use.

If you go down to a 14" wheel, and it changes the diameter of the tire you are using, you will have speedometer problems, and possibly engine control problems.

Answer 5

Check the prices on some of the tire sites like tirerack. I have yet to find a lot of difference in 15 and 14 inch sizes. When you go to 16 or larger the price really goes up.

Answer 6

it depends if u do then there be a loss of traction which is not good. Yes it would save money but i don't think it is the best idea in the world. Also making the rims smaller will affect the cars handling and the rid comfort.

Answer 7

Yes you can, as long as the rim holes line up with with your lug bolts. The down side of going to a smaller size, is it may throw your transmission and odometer off. The larger the tire the more comfortable ride.

Answer 8

Surprised to hear your having problems finding 15'' tyres. Pretty common now. Wouldn't of thought it would make a ton of difference in price to put 14" on instead of 15".

Do remember if you change the wheel size that the speedo will be out of calibration and will indicate the wrong speed.

Answer 9

As long as the car hasn't been modified in any way to take the new size, she should be able to simply buy a complete set of wheels with tyres.
Hmm, that'll be cheaper than 1 tyre!

Have you considered contacting your local Breakers Yard?
A lot of them do a tyre service that fits the good part-worn tyres onto your rims.
The 'life' of them isnt as long but at between £10 and £20 pounds (balanced) a hit, will that really matter?
Cheaper than 5 wheels with tyres.

Answer 10

Absolutely........I am tired of all these 20" rims coming standard on trucks.......makes tire cost NUTS. Downsizing wheels is the same as upsizing......you will end up buying a taller tire to keep the same mileage reading. If you downgrade to the exact wheel and tire option that came on the car before it was upgraded, you will be doing great!