Different tyre size than recommended by manufacturer.

CiniO

In my car users manual (03 Nissan Primera) it's stated that it can be equipped with tyres 205/60R16 or 215/50R17.

If I decide to put different size (205/55/R16) will the car be still road legal?
I understand that I have to inform my insurance company, but won't they say then, that's not homologated tyre size for that car, and it can't be driven like that?

Also the tyres that I want to put have speed index T (190km/h) and car maximum speed according to manufacturer is 194km/h so it actually will be able to exceed specified in tyre speed index.

How all this affect me being road legal?

PS. That tyres are only 2.05 cm smaller in diameter then manufacturers one, so difference is little. The difference in speed will be 3.24%, so in other words when my speedo show 100km/h I'll be driving only 96.76 km/h. (in reality it will be even less, because speedos always bigger speed then real anyway).

coylemj

The number following the 'R' is the rim diameter of the wheel the tyre will fit on to (the 'R' stands for radial) and since you've quoted two different numbers you need to be aware that if your existing tyres are (let's say) 16 and you want to buy xxxx R17 tyres then you will need to buy new wheels.

I calculate the diameter difference between those two tyres you quoted as 5.6 mm.

I don't see why you'd need to tell your insurance company if you fit tyres that conform to the specifications laid down by the manufacturer.

As far as being 'road legal' is concerned, the numbers you are quoting exceed the maximum speed limit in Ireland so I can't see how there could be a problem i.e. in order to test the 'road legal' status of the tyres you'd need to drive at 194 kmh in which case the Gardai wouldn't be much concerned with your tyres and more about your sanity. If (as I suspect) you're asking the question: Do my I have to fit tyres capable of handling the maximum spped of my car? I think the answer is 'no' because as far as I'm aware the Gardai only care about the amount of tread on the tyres and that the sidewalls are not damaged, the speed rating doesn't come into it.

CiniO

coylemj wrote: »

The number following the 'R' is the diameter of the wheel the tyre will fit on to and since you've quoted two different numbers you need to be aware that if your existing tyres are (let's say) 16 and you want to buy xxxx R17 tyres then you will need to buy new wheels.

No. No.
That two sizes are listed in car user's manual, as the allowed sizes.
My car is equipped with 205/60/R16, but I want to put on tyres 205/55/R16, which are not listed as allowed size.

I calculate the diameter difference between those two tyres you quoted as 5.6 mm.

That's the difference between 205/60/R16 and 215/50/R17.
Maybe I didn't write it clear enough, but I have actually 205/60/R16 and want to put 205/55/R16.
Difference there is 20.5 mm which is 2.05 cm

I don't see why you'd need to tell your insurance company if you fit tyres that conform to the specifications laid down by the manufacturer.

Again misunderstanding.
I want to put tyres that don't conform to the specifications.

As far as being 'road legal' is concerned, the numbers you are quoting exceed the maximum speed limit in Ireland so I can't see how there could be a problem i.e. in order to test the 'road legal' status of the tyres you'd need to drive at 194 kmh in which case the Gardai wouldn't be much concerned with your tyres and more about your sanity. If (as I suspect) you're asking the question: Do my I have to fit tyres capable of handling the maximum spped of my car? I think the answer is 'no' because as far as I'm aware the Gardai only care about the amount of tread on the tyres and that the sidewalls are not damaged, the speed rating doesn't come into it.

In Ireland OK.
But I'm perfectly allowed to travel with this car anywhere in EU, and there are places, where doing 194km/h is legal. That's actually my concern - what insurance company will say about it.

colm_mcm

I think Its safe to assume that the op has 16 inch wheels already and that I'd wants to know I'd fitting a different than standard tyre size would fail an nct or lame him in bother if he was in an accident.

What's the reason for changing?

CiniO

colm_mcm wrote: »

I think Its safe to assume that the op has 16 inch wheels already and that I'd wants to know I'd fitting a different than standard tyre size

That's exactly what I mean.
Maybe I didn't write it clear enough.

would fail an nct or lame him in bother if he was in an accident.

It's definitely no problem for NCT.
My only concern is in case of accident.

What's the reason for changing?

I have a set of winter tyres in size 205/55/R16 used only for 3 months last winter on my previous car. I changed the car, but kept the tyres.
As they are only 1 size different (205/55 to 205/60) I want to use them, but now I started wondering if it will be actually legal.

coylemj

Sorry, I didn't pick up that you were proposig to install a different size to the ones quoted by the manufacturer. I agree with the 2.05 cm diameter difference.

I think if the manufacturer states specific sizes and you deviate from this then it would be a notifiable modification i.e. you should tell the insurance company.

On the speed issue, I'd say that there wouldn't be a problem as long as you drive within the tyres' stated speed rating but if you want to be 100% certain you'd need to ask the insuance company as I'm sure no two of them have the same policy.

colm_mcm

Primera 1.6 top speed is 185 kmph

CiniO

colm_mcm wrote: »

Primera 1.6 top speed is 185 kmph

According to data I have it's 190 km/h.
Anyway I have 1.8 which top speed is 194km/h.

kirving

I can't imagine it would matter a whole lot from an insurance point of view, it's not eacctly a huge modification. ( I know the Ford Focus lists about 4 different tyre sizes for each model. But purely for fuel consumption data.)

peasant

I'd say don't worry.
Tyres of the same size differ in diameter between manufacturers and/or profiles anyway and the difference between a new and a barely legal tyre would also be something around the 15 mm mark in diameter.
Also a winter tyre would probably be slightly bigger than a summer tyre.

Your car will be a fraction quicker off the lights but slower in topspeed ...I don't see why that should worry your insurance.

CiniO

peasant wrote: »

I'd say don't worry.
Tyres of the same size differ in diameter between manufacturers and/or profiles anyway and the difference between a new and a barely legal tyre would also be something around the 15 mm mark in diameter.
Also a winter tyre would probably be slightly bigger than a summer tyre.

Your car will be a fraction quicker off the lights but slower in topspeed ...I don't see why that should worry your insurance.

I know all that. And I also don't see why should it worry my insurer, but Irish insurers seems to be worried about millions of things that are not important at all.

CiniO

CiniO wrote: »

I know all that. And I also don't see why should it worry my insurer, but Irish insurers seems to be worried about millions of things that are not important at all.

In that case just ring them and see if they are ok or not with it.