It seems that I have the option to fit different size alloys to my car. I cango for 15-16-or 17 in the wheels on the cata re 15 in but these have replaced the original alloys at some point. The tyres i have are all fairly new and i dont really want to trade on swop them at this stage, however it seems that the wheel styles in that size are limited and in any event I would prefer to go bigger than the 15x5.5j that are on there any advice please.
2007-07-04 09:36:12 · 5 answers · asked by oilman 2 in Cars & Transportation ➔ Maintenance & Repairs
The drive ration and mpg will change very little in the range you are talking about. You will not be able to notice the difference either way. I would go for the larger wheels because I prefer to have as much rubber on the ground as I can get. The changes in mpg will be in the hundredths of a percent. The only way to see any real change is to change gears in the rear end. Or you could cut off the fenders and run 24 inch truck tires or some such. Tractor tires would really give you a change. But kidding aside, normal tire sizes from largest to smallest will not change the gear ratio or mpg at all for practical purposes. The only noticeable difference is like I said, in traction.
2007-07-04 09:57:46 · answer #1 · answered by ed m 2 · 0⤊ 1⤋
Wheel size is vitally important to the final drive ratio of any vehicle.
If upsizing from standard 14" wheels, you need to keep the 'rolling radius' the same, that is, the rolling circumference of the wheel. To achieve this with a larger size wheel you need a smaller profile of tyre.
e.g. standard: 175/65/14 = 195/55/15 = 205/45/17
Notice the middle figure decreases as the wheel size increases. This is in order that you rolling radius remains the same.
Otherwise, your speedo reading would be over by a few mph at 30 and as much as 10mph (or more) at 70, enough to get you into trouble.
Increasing the size of your wheels will enhance the handling of your car, more noticably in cornering, because there is more rubber on the road but because of the increase of footprint, there will be a fuel penalty, typically 10-15% increase, depending on your driving style.
Make sure, also, that the offset is correct. If they are not, there will be problems on full lock steering and rear wheelarch fitting. If you are intending lowering the car, make sure there will be enough rear wheel arch clearance.
Hope this answers the question.
Happy motoring.
2007-07-04 17:10:56 · answer #2 · answered by Room_101 3 · 2⤊ 0⤋
Oilman, I've got a great site for you: Tirerack.com has a tire specification chart on every tire they sell. If you think about it for a second its the tire circumference that either raises or lowers your gear ratio plus messing up your speedometer. On the specification chart on this site in the column to the far right you will see the letters RPM at the top. In tire language they mean "Revolutions Per Mile".
If you first look up your standard wheel / tire size you can start to map out a larger diameter tire with a lower aspect ratio that will keep your speedometer close. Generally speaking a tire that makes 15 - 20 less revolutions (bigger circumference tire) per mile, will only make your spedo. less than a mile of an hour slower. As you see wheel size really doesn't mean anything but tire circumference does.
2007-07-04 16:59:03 · answer #3 · answered by Country Boy 7 · 1⤊ 0⤋
the larger the wheel the less work the engine has to do to cover a greater distance. the smaller the wheel means more work and higher revs. maclaren.
2007-07-04 18:03:41 · answer #4 · answered by maclaren 4 · 1⤊ 0⤋
please check ; in most countries it's illegal to change sizes.
2007-07-04 16:47:00 · answer #5 · answered by Julie 5 · 0⤊ 0⤋