Installing Larger Wheels

[Deelectro]

Hi, I have researched quite a bit about upsizing the wheels on a small car, but still not sure if it is the right thing to do. The OEM wheels on this small economy car are 15 inches. I would like to move up a little bit to at least 16.

The problems that have been associated with increasing wheel size include increased stress on the transmission, and brakes, It could also cause the speedometer to register incorrectly (not a big deal here). I'm wondering if anyone with actual experience can attest to these findings. So far what I have read was a lot of conjecture, but nothing conclusive.

[tifino]

If I can find them again, I'll post a link to a great Wheel/Tyre calculator.

In my example: Last month I had wanted to go from a 185/70/14, to a 185/75/14, a simple quest, yes?

my case was only for the tyres, and your query about wheels still goes along the same lines...

So anyhows, I rocked along and voiced my request to the local tyreman, who did his calcs too.

My calcs came up with exactly 3% increased rolling distance, but his came up as 3.05, so I did not proceed...

One of my intentions, in doing the change, was to compensated for the massively over-displayed speed difference between my speedo, and my GPS. An approx 3% increase still left me on the better side of the margin of error.

If you want to be worried about what your Insurance would have to say, just go over the wheel sizing label for your car, and work out the variations your car model is allowed...

my bottom-line hassle was that my mazda stipulated 185/70-14 over the entire range of model sub-variants

but I think next time, I'll just go ahead & do it

Edited September 3, 2014 by tifino

[giddyup]

What about bigger wheels but lower profile tyres?

[tifino]

What about bigger wheels but lower profile tyres?

that fits the formula for the rolling distance, wheel arch clearance, tyre width etc etc

just factor in that lower profile tyres are more expensive, harsher ride - especially for a little car, but apart from that...

[Spoonman]

If you stay within 3% of the OEM rolling diametre the noticeable difference will be very little.

Here is a comparison of tyre sizes as Iam going to upgrade from the 18" wheels/tyres on my Mazda 3, Iam thinking 19's but 20's is also a possibility.

A slighty harsher ride I do not care about as I will be fitting 1 inch lowered suspension as well.

Edited September 3, 2014 by Spoonman

[Deelectro]

_{Hi, thanks for the good info. definitely not interested in lowering the profile for those reasons given, and also style preference.. So will have to see about this 3% rule. All the guys at the Mag shops said going from 15-17 would be "no Problem" TIT 555}

Edited September 3, 2014 by Deelectro

[Spoonman]

Keeping the same tyre width/section profile as OEM and going to a larger rim diametre will make a noticeable difference to the vehicle but will make any noticeable improvement to handling (possibly making it worse with cornering and braking).

If you are only thinking about aesthetics just go to an alloy rim that you like in the same diametre as OEM and keep your existing tyres.

Edited September 3, 2014 by Spoonman

[tifino]

here's that Link that I went by:

http://www.exploroz.com/Vehicle/Tyres/SizeCalc.aspx

I used the comparison at the bottom, and found having an aspx page for data entry just that little bit more convenient

it'll suit 4wd nuts too!

for my 185/70/14 example, which BTW is still on the mazda; my speedo reads:

107kmh, for a GPS 100kmh

100kmh, for a GPS 92kmh

so according to the calculator, my speedo would still read higher than the GPS even with 185/75-14 tyres fitted.

Edited September 3, 2014 by tifino

[J4M35]

As Tifino says, your speedometer already reads incorrectly- it is quite usual for them to over-read by as much as 10%. This is a deliberate design feature included by manufacturers. In reality, therefore, you could probably fit higher profile tyres (greater than 3% difference) without your speedo under-reading.

However I'd question the 'why'? Your car has 15" wheels as standard. You tell us that you want bigger wheels while retaining an equal tyre profile to retain ride comfort, while retaining roughly equal driving characteristics? It is not possible, something has to give.

You have a number of issues. For a start, 16" tyres are less common and more expensive than 15". 16" wheels will in all probability be wider than your 15" ones which means wider tyres which are more expensive and will also reduce your fuel economy. You'll also end up with a greater rolling circumference which will reduce your acceleration. You'll also increase your ride height and center of gravity. They may also be heavier which will reduce ride comfort and handling. You could fit 17" wheels but all of these problems will still be present and to a greater extent (apart from tyre prices which will be more reasonable) and wheel/arch clearance might start to become a problem.

Of course you could fit lower profile tyres to maintain a simular rolling circumference but you'd compromise ride comfort and increase the risk of wheel damage.

Like Spoonman, I'd suggest finding a 15" wheel you like and keeping your standard tyres. If you really must go bigger, fit 17" wheels with high quality lower profile tyres (i.e. Michelin) which will ride smoother and quieter than a cheap low profile tyre (but still not as smoothly as a quality tyre in OEM size due to increased width and unsprung weight)

[culicine]

If you stay within 3% of the OEM rolling diametre the noticeable difference will be very little.

Here is a comparison of tyre sizes as Iam going to upgrade from the 18" wheels/tyres on my Mazda 3, Iam thinking 19's but 20's is also a possibility.

A slighty harsher ride I do not care about as I will be fitting 1 inch lowered suspension as well.

Spoonman, be careful with the lowered springs. Many quote 20-30mm drop, but I found when I used them, the drop was closer to two inches. If you have the cash get some adjustable coilovers. They cost more but you can adjust. Not sure if you can set them to just a 1inch drop though. I have 17" on my civic. Can't imagine 19 or 20" lol. They will be rather harsh and you will have hardly any sidewall left. They will look cool though! Watch the flooding roads too:)

[Spoonman]

Spoonman, be careful with the lowered springs. Many quote 20-30mm drop, but I found when I used them, the drop was closer to two inches. If you have the cash get some adjustable coilovers. They cost more but you can adjust. Not sure if you can set them to just a 1inch drop though. I have 17" on my civic. Can't imagine 19 or 20" lol. They will be rather harsh and you will have hardly any sidewall left. They will look cool though! Watch the flooding roads too:)

Yeah am fitting a koni/eibach combo that is popular with 3 owners in the USA, never heard of any reports that the vehicle is lower than expected.

My 3 already has 18" wheels so the jump to 19" or even 20" is not as extreme as it sounds... vehicle performce on flooded roads will be the same no matter the wheels fitted.