MPG Vs. Wheel/Tyre Size

Delivery_Driver

Less power needed to accelerate with a smaller/lighter wheel and can make the handle better(unsprung weight) and car nicer to drive.
More inertia with a heavier wheel so gains from that to if you don't do alot of stop/start driving.
The biggest savings are more likely to be in the price of the tyres themselves.

supermanjo

I know the quality of the tyre, pressure, width etc makes a difference but that’s not the question. Lets say all of these are the same...

To simplify the question:

If a 15" wheel with a bigger tyre and a 17" wheel with a smaller tyre have the same circumference, will there be a difference in MPG? (same width, same brand, same driving style, same everything.)

Thanks!

Delivery_Driver

Are the wheels the same?Huge difference between the weight of wheels.
Your question has already been answered btw.

supermanjo

Delivery_Driver wrote: »

Are the wheels the same?Huge difference between the weight of wheels.
Your question has already been answered btw.

Hypothetically speaking, yes, same make and model however smaller which means a lighter. This is what I'm asking, will having a bigger tyre (wall) decrease MPG over having a bigger wheel (increased weight) but with a smaller tyre (wall.)

Thank you.

Lum

The 17" wheel is probably heavier which will, as stated above, hurt you if you do a lot of stop/start driving, but help you if you do a lot of motorway cruising.

However we are talking tiny differences. Chances are the biggest hit to the wallet/purse will be the increased cost of low profile tyres for the 17s, as Mikey72 alluded to. Looks like the difference is around £15-£25 per tyre for a premium brand.

Delivery_Driver

Its swings and roundabouts.A 15" wheel is going to be a lot lighter than a 17" one but will be using a tyre with a higher(and so thicker to help stop it flexing) sidewall, increasing the weight of the tyre disproportionally compared to the 17" tyre with the lower sidewall.There could be just as much rubber in the smaller tyre, or even more and tyres are heavy.

sunshinetours

Main point assuming this is a real world question on which you are basing a decision, is that 15" tyres almost certainly will be cheaper x 4 and that will outweigh any absolute marginal differences in mpg savings either way.

sally78

sunshinetours wrote: »

Main point assuming this is a real world question on which you are basing a decision, is that 15" tyres almost certainly will be cheaper x 4 and that will outweigh any absolute marginal differences in mpg savings either way.

No becuase the 17" will be 205/40 and the 15" will be 205/65 so the same ammount of rubber will most probbally be used.

vikingaero

sally78 wrote: »

No becuase the 17" will be 205/40 and the 15" will be 205/65 so the same ammount of rubber will most probbally be used.

Strange reasoning!

When you buy lower profile tyres there are often other factors that will affect the cost more on the lower profile tyre:

- more advanced tread design on 17's = more cost
- larger market for 15's = economies of scale
- 17's more likely to use advanced construction such as kevlar
- generally higher speed ratings on 17's

Lum

Also low profile tyres = generally more sporty car = higher markup.

If only there were websites where you could look up prices of tyres and see for yourself which are more expensive.