Tyre Load Ratings / Speed Ratings

C

CornishRob

Senior member
HI Chaps,

Looking for some advice.

I'm looking at sorting some tyres for my car soon. Z4MC.

I will be swapping the current MPS2 to MPSS. I am thinking about also going up a size from 255/40 to 265/40 as many people on here seem to have done.

One of the positives of going up a size is that Tyre Leader have the 265 at £158 while the 255 are £197 in OE fitment.

The OE fitment is 95Y I think. They have a 255 with 99Y for £172 which could be an option over the £197 priced OE Spec.

They 265 they have for £158 is 101Y.They don't have the 265 size in any other load/speed rated option.

Now my question is, what difference will I feel if I go for the extra loaded/speed tyres (265 101Y) or the (255 99Y) over the current OE spec.

Can anyone offer any advice?

Will they be extra stiff and make the ride worse or similar?
 
They will be better at 180mph ish :D

Look at the info on Michelins site, much easuer to get an idea. Basically you need the extra load, and with the PSS i think they all are, and will all be suited to the M.
 
Thanks to the folk who like there big fat tdi 4x4's, there is a decent selection of high load rated tyres. The only problem is they seem to be getting bigger & bigger, bling, wheels on them, so there may be less choice in a few years time for our poxy 18's. Many are rated to above the M's top speed, on a car that ways a relatively sprightly 1450kg or so. I don't no any thing about modern tyre construction, but I would hazard a guess that the side wall are stiffer than they need to be on a sports car, where the same tyre can also be used on a big fat slightly slower 4x4.

(Did I mention 4x4's are big and fat and often powered by the fuel of saten) :poke:
 
So had a look at the Michelin website. Doesn't really say much apart from giving the OE tyre sizes and recommending the PSS. Obviously doesn't suggest changing to a different size.

Does say Developed with Porsche, BMW M & Ferrari.

I understand the difference between the speed ratings and load ratings, but what I am trying to find out what difference I may feel, it any between say a 101 Y & 95 Y.

Madforslalom sent me some pics of his car running 265 rears and 235 fronts, but he also has 10mm spacers, but looks great on 224s from what I can see.

Obviously I want to make sure what I buy will be good as I don't want to end up with a setup I'm not happy with.
 
Rob,

I've just had some Michelin PSS' delivered.

I've gone for:

225/45/R18 95Y
255/40/R18 99Y

I had a similar conundrum to you in that the 95Y was available in 255 size, but was £30 a corner dearer. I would imagine that the sidewall of the 99Y will be stiffer, but I'm not sure how much difference I will actually feel.

Having them fitted towards the end of next week so I'll let you know how they feel.

I'll also post some photos of how they look. I'm running 224's with Eibach pro kit springs, and no spacers.

I was tempted by the 265/235 sizes, I do like the chunkier look but was concerned that they would rub with the lower springs.
 
As for Insurance, I've no idea whether you'd have to inform them, I would imagine that most car owners wouldn't know if their tyres were slightly different to OEM spec.
 
Yes I am too. Currently running PS2 so hoping for an improvement although to be fair, I haven't had any issues with them! Always nice to have fresh tyres though!

I'm nearly down to the wear markers, which is a bit naughty for this type of car, but been so busy I haven't ha a chance. Finish work in 2 weeks, so will be sorting then!

Just need to decide about which size!
 
StevenH72 said:
Rob,

I've just had some Michelin PSS' delivered.

I've gone for:

225/45/R18 95Y
255/40/R18 99Y

I had a similar conundrum to you in that the 95Y was available in 255 size, but was £30 a corner dearer. I would imagine that the sidewall of the 99Y will be stiffer, but I'm not sure how much difference I will actually feel.

Having them fitted towards the end of next week so I'll let you know how they feel.

I'll also post some photos of how they look. I'm running 224's with Eibach pro kit springs, and no spacers.

I was tempted by the 265/235 sizes, I do like the chunkier look but was concerned that they would rub with the lower springs.
Click to expand...

How did you get on with the 99Y rated rears? Did it make a difference?
 
CornishRob said:
Also do people tell their insurance if they change the tyres size?
Click to expand...

You must tell them. If you've changed from the approved/oem spec. as delivered.
Firstly it may well be classed as a performance enhancement and an increase in risk and it can be used against you if there's any sort of incident, especially if they can cite tyres and a contributory factor. Payout could be withheld, etc.

There may be a minor argument that it's OK if they are on the approved list for that make and model (label on the car)
 
cj10jeeper said:
CornishRob said:
Also do people tell their insurance if they change the tyres size?
Click to expand...

You must tell them. If you've changed from the approved/oem spec. as delivered.
Firstly it may well be classed as a performance enhancement and an increase in risk and it can be used against you if there's any sort of incident, especially if they can cite tyres and a contributory factor. Payout could be withheld, etc.

There may be a minor argument that it's OK if they are on the approved list for that make and model (label on the car)
Click to expand...


I went for the OEM sizes and loads in the end. MPSS all round.

I got them from Oponeo
 
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