Technical Michelin CrossClimate +

[gar074]

With apologies for reviving this old thread...

I've just been pricing up a set of these. In my size (185/65 15) they only seem to be available in a T (118mph) or V (149 mph) rating. My original-fit Goodyear Vector 4Seasons are H (130 mph) rated, which is what Fiat specifies for the 4x4 and the Cross, but curiously the non-4x4 Panda TA is specified with T rated tyres, even though it has a higher top speed than the 4x4/Cross TA!

Bit of a bummer, as there are great deals on T-rated CrossClimates at the moment, but the V rated ones are a fair bit more expensive.

Anyone care to hazard a guess as to why Fiat specifies the 4x4/Cross as needing H rated, not T rated, when their top speed is lower than the non-4x4 versions, and where all versions of the Panda would struggle to get anywhere near 118mph?

Also, the CC+ are XL rated, whereas the Goodyears are not. Am I likely to notice any difference in the driving characteristics because of the stiffer side-walls?

 

[oyumurtaci]

With apologies for reviving this old thread...

I've just been pricing up a set of these. In my size (185/65 15) they only seem to be available in a T (118mph) or V (149 mph) rating. My original-fit Goodyear Vector 4Seasons are H (130 mph) rated, which is what Fiat specifies for the 4x4 and the Cross, but curiously the non-4x4 Panda TA is specified with T rated tyres, even though it has a higher top speed than the 4x4/Cross TA!

Bit of a bummer, as there are great deals on T-rated CrossClimates at the moment, but the V rated ones are a fair bit more expensive.

Anyone care to hazard a guess as to why Fiat specifies the 4x4/Cross as needing H rated, not T rated, when their top speed is lower than the non-4x4 versions, and where all versions of the Panda would struggle to get anywhere near 118mph?

Also, the CC+ are XL rated, whereas the Goodyears are not. Am I likely to notice any difference in the driving characteristics because of the stiffer side-walls?

It all has to do with the construction of the tyre and the physics of going faster. The tread face of the tyre is constructed so that the tread can create a contact patch. When you go faster, however, the centrifugal force of the spinning tyre pushes the thick, heavy tread face outwards. Since that face is only really connected to anything at the very edges (the sidewalls), the middle bit tends to bow outwards at higher speeds, creating less and less of a contact patch and more stress on the tread face of the tyre because it's bending outwards, being pulled out by the centrifugal forces of spinning but having a smaller contact patch carrying the weight of the vehicle (centripetal force) and all the friction of the road surface is accumulating in a smaller and smaller spot, creating hotspots on the tread surface and within the tyre while also increasing tyre pressure because the air in the tyre is getting heated up.

That's the physics of tyres going fast, so what can be done about it? Thinner tyres have less width in the tread face, so they tend to bow less at speed. Higher speed ratings on tyres mean the part of the tyre carrying the tread has been constructed in a way that it will bow less. A heavier car will apply more stress on the contact patch regardless of speed, so using a higher speed rated tyre on a heavier vehicle (even if it can't go that fast) will benefit grip and safety. Also, the reinforcement that usually applies to higher speed ratings also work in the other direction, so tyres with higher speed ratings are less likely to puncture.

Adding to all of this, the sidewalls of tyres also need to be built strong enough to handle keeping all that centrifugal force coming from the tread face connected to the bead and rims. Therefore, higher speed rated tyres usually also have stronger sidewalls to deal with the added forces. XL (extra load) tyres, however, are designed with extra vertical load (vehicle weight) in mind with more sidewall reinforcement that doesn't necessarily increase the speed rating (because the load isn't centrifugal from speed, it's from carrying heavier loads so it can withstand greater vertical (or centripetal) pressure. Because of this, XL tyres usually have reinforced sidewalls that make them harsher rides (because they have less 'give' when they hit a pothole and reverberate more due to the added stiffness) but tend to deal with adverse conditions (off roading, hitting potholes etc.) better with less likelihood of failure.

Now, as far as how reliable ratings are, it's a double edged sword. A T rated tyre is essentially saying that it can reliably reach that speed, but may fail once that speed is reached. Tyre ratings can't account for, say longevity. Therefore, one T rated tyre may live life as a motorway cruiser for many years, while another might shred itself its first time out on the derestricted autobahn. Since, however, I don't live in Germany, I personally would go with the good deal on the T rated, especially considering they are also XL rated (which increases the longevity and reliability of use case scenarios not actually involving extra loads). As far as NVH from the XL rating, the TwinAir and Multijet engines become a nuisance far earlier than the tyre noise, but they do tend to bounce about a little more than regular tyres. Still, they're nowhere near as bad as run-flats.

 

[R1NGA]

Anyone care to hazard a guess as to why Fiat specifies the 4x4/Cross as needing H rated, not T rated, when their top speed is lower than the non-4x4 versions, and where all versions of the Panda would struggle to get anywhere near 118mph?

... this is Fiat we're talking about remember - they're not known for clear and consistent information about anything. Just get the H-rated versions and they will of course be just fine.

 

[gar074]

Just had a set of Michelin CrossClimate+ fitted, to replace the Goodyear Vector 4 Seasons.

First impressions - the ride is noticeably firmer than before (not surprising, as the Michelins have a 92 XL load rating, whereas the Goodyears are rated 88), and the steering feels sharper (again, not surprising, due to the stiffer sidewalls). So far, I'm content with that trade-off.

Can't wait to see how they perform in the snow (and I may not have to wait all that long )

 

[The Panda Nut]

my Conti mud and snows are at 6.5mm after 15000 miles. Dry weather understeer is noticeable but not in any way a problem. Other than that performance is good and snow not even detectable! Would not hesitate to buy more. I suspect the tyres will outlast he engine.

 

[Alsatian1]

my Conti mud and snows are at 6.5mm after 15000 miles. Dry weather understeer is noticeable but not in any way a problem. Other than that performance is good and snow not even detectable! Would not hesitate to buy more. I suspect the tyres will outlast he engine.

Just shod my Trekking in more of those. I went with cheaper winter tyres last year, and they were terrible in the snow. I find the Conti cross contacts quite difficult to source, but definitely worth it when the bad weather hits.

 

[gar074]

Just had a set of Michelin CrossClimate+ fitted, to replace the Goodyear Vector 4 Seasons.

First impressions - the ride is noticeably firmer than before (not surprising, as the Michelins have a 92 XL load rating, whereas the Goodyears are rated 88), and the steering feels sharper (again, not surprising, due to the stiffer sidewalls). So far, I'm content with that trade-off.

After a quick blast along the A14/A11 this morning, I can confirm that the Michelins are also quieter than the Goodyears.

(Man alive, the wind noise from those wing-mirrors is bad. Not really noticed it before!!)