14inch or 15inch?

[Crinkle Cut Jasper]

Hi,

I have a 1995 N reg dimension 1.9td and a 94/95 M reg Sx 1.9td - lucky you i hear you all shout

Heres the question, the dimension runs on 15 inch steel rims & the SX runs on 14 inch steel rims both 185/65 (I think - ok its raining and dark outside).

Does anyone know why they are different or is this a really stupid question?

Also are there any benefits from having the larger or smaller size?

Just a thought.....

cheers

jas

[Mandrake]

15" steel rims ?

I thought the Xantia only came with 14" steel rims or 15" alloys ?

As for whether the 15" is any "better", how long is a piece of string ? Ask 10 people about wheel sizes and you'll get 10 different answers...

Regards,
Simon

[Homer]

Heres the question, the dimension runs on 15 inch steel rims & the SX runs on 14 inch steel rims both 185/65 (I think - ok its raining and dark outside).

Have a play around with the figures on this calculator or this one.

The second calculator warns that the 15" ones are possibly too large.

[mezuk04]

Xantia?
Xsara?
Zx?

?

[Village]

how long is a piece of string ?

Twice as long as half its length.......

why not go the Pimp My Ride route and slap some 20" chrome spinners on it!

[Crinkle Cut Jasper]

Sorry, forgot to add, its a xantia

cheers

[jeremy]

As you have probably gathered wheels and tyres are rather dependant on maths.

The easy bit is the 14 or 15 which is the wheel diameter in inches.

The 185 bit of the tyre size is its tread width in mm
The 60 or 70 etc is the 'Aspect ratio' which is the ratio of tread width to wall height. In the absence of any figure radial tyres have an aspect ratio of 80% and crossplies of 90% and so for a 195 x 60 tyre the wall height is 60% of 195mm (117mm)

So you can now work out the diameter of a tyre from its dimensions

Wheel diameter
plus 2 x wall height = diameter. (remember to use the same units!)

So 195 x 60 x 14 = 589.6 mm (23.21 inches)

Now you can work out if your wheel and tyre combination will fit - assuming the rims have the same offset and you are not using excessively wide tyres.

[RichardW]

The original tyre size should be quoted on the tyre pressure sticker on the drivers door A pillar. The original cars came on 14" steels or 15" alloys for the higher spec cars (I think the alloys were something like 205/55 15). Later they changed to 185/65 15 steels (and alloys - my 97 VSX has 185/65 15 alloys, whereas my 95 LX had the same size steels.) Not sure why they changed - aesthetics perhaps? Those who have driven plenty usually reckon that the ride is better on the original 14" wheels. Ride is much better in my Hydractive VSX than the LX though!

[f00lzz]

Surely the ride would be smoother with 15"

[Village]

I think the extra height on the sidewall of the 14" wheel would give a more compliant ride, more height means more room to flex.

[jeremy]

Village yoe I'm sure you are right - and another thing that must be considered is the volume of space for the air.

If the space is very small then on hitting a bump the pressure increase will be considerable. Some years ago Porsche found this such a problem they used alloy wheels with hollow spokes to increase the available volume and improve the ride.

[Kowalski]

I think the extra height on the sidewall of the 14" wheel would give a more compliant ride, more height means more room to flex.

Both tyre profiles he quotes are 185 65, i.e. the same width and sidewall height.

In theory a larger wheel should give a better ride but if the tyres are a different speed rating, the sidewalls could be thicker.

The difference I noticed about the larger wheels was the gearing, the larger wheels will give you slightly taller gearing than the smaller ones when you're talking about the same tyre sidewall height.

[Peter.N.]

Smaller wheels with larger tyres are what will give you the best ride, some of these modern cars with 'bicycle tyres' shake your teeth loose.

[reblack68]

My Xantia has 195/60 tyres on 15" steel wheels. I must admit I'm strongly tempted to replace them with 185/65s, because that's what it is meant to run on.

I read an article once that claimed Minis handled best on 145x10 tyres and that anything wider just meant you got less warning before they let go. I think that principle probably applies to a lot of cars.

[Mandrake]

My Xantia has 195/60 tyres on 15" steel wheels. I must admit I'm strongly tempted to replace them with 185/65s, because that's what it is meant to run on.

I read an article once that claimed Minis handled best on 145x10 tyres and that anything wider just meant you got less warning before they let go. I think that principle probably applies to a lot of cars.

I wouldn't do that.

I changed mine from 185/65/15 to 205/60/15 and the handling and grip is MUCH better. My Dad's Xantia also has 195/65/15 and it too has more grip than the 185's gave. (Interesting thing is the door stickers on his car actually say the originals are 195/60/15 while my door sticker says 185/65/15 even though mine is a VSX and his is an SX, and they both have the same engine )

When you say that that size is what it's "meant" to run on, the default tyre size is just as much about the spec of the car - some models like the turbo CT, 16v, or V6 come with 205/55/15 or 205/60/15 as standard. (Although to be fair the V6 is quite a bit heavier)

Having said that I think 205/60/15 is fairly close to the sensible limit for a standard performance Xantia, I wouldn't go any wider than that...

Regards,
Simon