General Tyre size

[Steve Selvage]

I have a 500 lounge arrive with new Bridgestone 185/65/15 tyres on the back and 2 knackered 185/55/15 on the front.
Can I fit a couple of new 185/65/15 on the front and have a matching set or should I buy all four of the correct size?
Is it ok to have bigger tyres on a 500?

 

[Greasytrucker]

If it’s only meant to have 55 profile tyres on it i wouldn’t recommend tyres with a taller wall on the front or back, it’ll throw your speedo out and on the front there’s a risk of fouling when you turn the steering. Get a full set of the correct size

 

[vexorg]

I would recommend it if you dont like bone shattering knocks from potholes, But only if you do the work and check how it will affect the speedo. and clearances.

I've gone from 40 to 45 on mine (non fiat) and it makes a world of difference to the comfort.

 

[Greasytrucker]

I would recommend it if you dont like bone shattering knocks from potholes, But only if you do the work and check how it will affect the speedo. and clearances.

I've gone from 40 to 45 on mine (non fiat) and it makes a world of difference to the comfort.

I’d just be a bit concerned on clearance especially on the front if jumping up from a 55 to 65. Agreed ride will definitely be softer

 

[John202020]

Look on the plate on the door jamb on the car for the correct size, then have all four the correct one.
Don't buy any XL rated size
Go with the highest correct size profile

 

[AnthonyH]

I have a 500 lounge arrive with new Bridgestone 185/65/15 tyres on the back and 2 knackered 185/55/15 on the front.
Can I fit a couple of new 185/65/15 on the front and have a matching set or should I buy all four of the correct size?
Is it ok to have bigger tyres on a 500?

You should drive whatever size tyre was originally fitted to the car by the manufacturer. If you're tyres are higher overall then you're speedo will say you're driving more slowly than you are. This might mean you're caught out by speed cameras, end up with points on your license and bigger insurance premiums (Leaving aside more possibility of crashing because of speeding).

 

[steveras57]

Makes you wonder why there is two different sizes on it in the first place!

 

[AnthonyH]

Makes you wonder why there is two different sizes on it in the first place!

I'm not wondering. Two wheels got stolen! And the previous owner went down to the scrap yard and bought the cheapest he could get hold of

 

[There all puntos]

When it comes to speed, no matter what profile you chose, your rev counter still operates the same.

So keep a eye on what revs in top mean, what speed, like it tells you in most handbooks I e. 1200rpm in top means 28 - 34mph, etc, etc. (with the standard profile, but bald tyres front or back, as they turn quicker, and read more than brand new). It can never change even if you raise or lower the profile of tyres.


Unless your Speedos not working, then use lamp post distance, picket fence, other motorists. Or the Speedo app on a phone when your instruments are away getting fixed.

Like I did on my Punto and Stilo


Ps. If you chose to widen the 185x 55 to 195x 55 tyres, the side wall will be bigger, as the 55 index is just over half the width of the tyre. Works the other way too.

 

[Steve Selvage]

The tyres on the back are new Bridgestone tyres, not scrap yard specials, I have had cars in the past with slightly bigger tyres on the back and it's perfectly legal as long as the back tyres are the larger ones and the same size across each axle.
The reason I ask is to see if a 65 ratio tyre would work on the front as the front tyres are worn and it would be cheaper to put 2 more Bridgestone tyres on the car rather than change all four.
There is no sticker on the door pillar of any 500 that I've seen to show the tyre size options.

 

[Greasytrucker]

The tyres on the back are new Bridgestone tyres, not scrap yard specials, I have had cars in the past with slightly bigger tyres on the back and it's perfectly legal as long as the back tyres are the larger ones and the same size across each axle.
The reason I ask is to see if a 65 ratio tyre would work on the front as the front tyres are worn and it would be cheaper to put 2 more Bridgestone tyres on the car rather than change all four.
There is no sticker on the door pillar of any 500 that I've seen to show the tyre size options.

I’m surprised we’ve not had the “it’’ll invalidate your insurance” brigade on here yet tbh! At the end of the day you sound like you know what you’re talking about so all you can do is try it. I’m not gonna preach and say it’s unsafe or any other derogatory comment, it either works or it doesn’t. I’ve done it myself (not 2 different profiles at the same time i might add though). We’re all on here to save money at the end of the day so try it and let us know. Only thing I will say is I tried a similar thing on my sons Fabia as a temporary measure and the car didn’t like different sizes front to back and it confused the ABS system. Good luck interestingly on the subject of speedos my sons Fabia actually read bang on correct on a Sat Nav rather than a couple of MPH slow like most cars with 55 profile as opposed to the correct 45 profile. We did have to modify the rear arch on one side to make them fit though!

 

[John202020]

There is no sticker on the door pillar of any 500 that I've seen to show the tyre size options.

You're correct my mistake, it's in the book

 

[Steve Selvage]

Thanks for the pic, unfortunately I have no book but as there's no reference to the bigger tyres in the pic I think I'll change all four for the correct size.
Many thanks for all the replies everyone

 

[vexorg]

I think people overestimate the effect profile height has on the speed.
My dashcam has a GPS speedo mode (what I normally leave it as the video image is annoying at night). At 64mph, the GPS speed was steady 62mph or the original 40 profile, and now flicks between 62 and 63mph on the 45 profile.
The pe may be a certain percentage bigger, but the tyre sidewall is compress n the ground due to the weight. Unloaded you might see a big difference, but the difference of rim to ground isn't that much when it's on the car.

What make are the tyres? and how much tread on them?

 

[AnthonyH]

I’m surprised we’ve not had the “it’’ll invalidate your insurance” brigade on here yet tbh!

To improve ride comfort and handling, tail fins are the best bet!

 

[AnthonyH]

I think people overestimate the effect profile height has on the speed.
My dashcam has a GPS speedo mode (what I normally leave it as the video image is annoying at night). At 64mph, the GPS speed was steady 62mph or the original 40 profile, and now flicks between 62 and 63mph on the 45 profile.
The pe may be a certain percentage bigger, but the tyre sidewall is compress n the ground due to the weight. Unloaded you might see a big difference, but the difference of rim to ground isn't that much when it's on the car.

What make are the tyres? and how much tread on them?

More or less every car I've had for the last 10 years or more has had a speedo that doesn't correspond to GPS.

The speedo always says I'm driving slower, I figured it was the manufacturers way of trying to make people slow down. Or maybe the GPS isn't so accurate.

 

[AnthonyH]

The Bridgestone 185/65/15 tyres aren't in the manual for this car according to John202020's manual.

So would this class as a modification?

 

[vexorg]

The speedo always says I'm driving slower, I figured it was the manufacturers way of trying to make people slow down. Or maybe the GPS isn't so accurate.

The accepted reasoning is that it reads high so that the manufacturer can never be held responsible for you getting caught speeding.

GPS speeds tend to be accurate.

 

[vexorg]

The Bridgestone 185/65/15 tyres aren't in the manual for this car according to John202020's manual.

So would this class as a modification?

That's between you and your insurance company to decide.
But generally would be a problem for a typical car, and only supercars have larger tyres on the rear, like the fiat F40

 

[Piccolo Nero e Bella]

More or less every car I've had for the last 10 years or more has had a speedo that doesn't correspond to GPS.

The speedo always says I'm driving slower, I figured it was the manufacturers way of trying to make people slow down. Or maybe the GPS isn't so accurate.

I believe they deliberately under-quote the speed because an accurate speedo would no doubt be more expensive and that gives them a bit of leeway; a couple of k's either way won't be noticed. My car's speedo reads 5kph slow at 100kph but I have a GPS HUD and it's spot-on. A Mazda 2 I drove once had an inbuilt HUD but it wasn't GPS so the speed data was still several kph under the actual.