Tyre profile VS sidewall stiffness?
Discussion
The local roads are very poorly paved, full of hideous potholes. They're a disgrace.
So naturally I want a quick car to drive on them. I could stick with 18" wheels and fit non-runflats but not all tyres are created equal. Some are very stiff regardless and some less-so. Is a stiffer, higher profile non-runflat 17" tyre a better choice for ride comfort over a softer, lower profile non-runflat 18"? Which would give better cornering (not the absolute highest priority but still very important).
The roads are really, really bad....
So naturally I want a quick car to drive on them. I could stick with 18" wheels and fit non-runflats but not all tyres are created equal. Some are very stiff regardless and some less-so. Is a stiffer, higher profile non-runflat 17" tyre a better choice for ride comfort over a softer, lower profile non-runflat 18"? Which would give better cornering (not the absolute highest priority but still very important).
The roads are really, really bad....
It's an E89, 35i so tipping the scales at around 1600kg. The smallest wheels are the seventeens, which mount 225/45 tyres front and 255/40 rear or 45 profile all around can be fitted perhaps, I'm told. An option on lower spec cars is 225 tyres all around, not the best idea with 300+ horsies. The car was optimised for Runflats but that'll be on German roads no doubt, not the Beirut we enjoy here.
I suppose the front tyre walls are stiffer but higher for the same amount of comfort as the softer, lower rears but improved steering response? Would that essentially mean getting XL tyres, which are stiffer, up front and normal rears? There's so much to consider; asymmetrical tread patterns can tramline badly on poor road surfaces, for instance i'm told, but as usual all tyres have confliciting reports and reviews. Michelin Pilot Super Sport? "Oh, these are noisy as hell" vs "These are very quiet!"... Vredestein Ultrac Sessanta? "Oh, you can mount kerbs with ease" vs "they offer NO rim protection!"...
It's because these reviews are from different cars of course, but it confuses the hell out of me...
I suppose the front tyre walls are stiffer but higher for the same amount of comfort as the softer, lower rears but improved steering response? Would that essentially mean getting XL tyres, which are stiffer, up front and normal rears? There's so much to consider; asymmetrical tread patterns can tramline badly on poor road surfaces, for instance i'm told, but as usual all tyres have confliciting reports and reviews. Michelin Pilot Super Sport? "Oh, these are noisy as hell" vs "These are very quiet!"... Vredestein Ultrac Sessanta? "Oh, you can mount kerbs with ease" vs "they offer NO rim protection!"...
It's because these reviews are from different cars of course, but it confuses the hell out of me...
Cheers for the advice lads.
So taking into account things like protecting the rims when they fall into potholes, a higher, stiffer profile on smaller rims is perhaps the best bet. This will keep the handling somewhat sports car-ish (I know it's more of a GT, but it looks sporty anyway, so it'd be nice to live up to that somewhat. If I was so adamant about comfort, I'd bite the bullet and get a C5, which however would be too big for these roads and wouldn't fit into my house without a seven point turn, in & another out...) whilst still hopefully offering acceptable comfort with the suspension in normal mode. I'll also get those black plastic rim protector affairs, unless they're a bad idea do you all think?
I've come in for criticism; the seventeens look daft, owners say. I disagree. I think they look pretty good; not too small, and besides the brakes fill them nicely.
These 514 style wheels are quite hard to get hold of; I'm not sure if they're lighter than the other staggered seventeens offered, which are actually slightly heavier than the popular 18" rims many Z4s wear...
Aftermarket wheels are a no-no for me after my previous car, although if I could find a nice set of lightweight OEM looking BBS style split rims with the right offset and rim width, I'd bite. No real luck so far; Italian laws forbid us from getting wider than OEM tyres, otherwise I'd go 245 front and 275 rear, to skim over smaller potholes...
So overall; for my driving conditions (mostly town, heavy traffic, hideously bad roads, with a good mix of (expansion joints every 30 feet) motorway miles, lots of high speed runs whenever I can) and style (very relaxed and comfortable around town, but wanting to keep momentum up, and wanting handling on-par with the car's looks) what's the best choice of tyre type? Asymmetrical treads look great but if they tramline, they're out. It very rarely rains although when it does, the right tyres are very important of course. No snow and the temperatures stay well above zero, so summer rubber should work all-year around barring the occasional treat-myself winter jaunt up the chilly mountain passes an hour or so away. I'll probably keep two tyre repair kits in the car for redundancy.
So taking into account things like protecting the rims when they fall into potholes, a higher, stiffer profile on smaller rims is perhaps the best bet. This will keep the handling somewhat sports car-ish (I know it's more of a GT, but it looks sporty anyway, so it'd be nice to live up to that somewhat. If I was so adamant about comfort, I'd bite the bullet and get a C5, which however would be too big for these roads and wouldn't fit into my house without a seven point turn, in & another out...) whilst still hopefully offering acceptable comfort with the suspension in normal mode. I'll also get those black plastic rim protector affairs, unless they're a bad idea do you all think?
I've come in for criticism; the seventeens look daft, owners say. I disagree. I think they look pretty good; not too small, and besides the brakes fill them nicely.
These 514 style wheels are quite hard to get hold of; I'm not sure if they're lighter than the other staggered seventeens offered, which are actually slightly heavier than the popular 18" rims many Z4s wear...
Aftermarket wheels are a no-no for me after my previous car, although if I could find a nice set of lightweight OEM looking BBS style split rims with the right offset and rim width, I'd bite. No real luck so far; Italian laws forbid us from getting wider than OEM tyres, otherwise I'd go 245 front and 275 rear, to skim over smaller potholes...
So overall; for my driving conditions (mostly town, heavy traffic, hideously bad roads, with a good mix of (expansion joints every 30 feet) motorway miles, lots of high speed runs whenever I can) and style (very relaxed and comfortable around town, but wanting to keep momentum up, and wanting handling on-par with the car's looks) what's the best choice of tyre type? Asymmetrical treads look great but if they tramline, they're out. It very rarely rains although when it does, the right tyres are very important of course. No snow and the temperatures stay well above zero, so summer rubber should work all-year around barring the occasional treat-myself winter jaunt up the chilly mountain passes an hour or so away. I'll probably keep two tyre repair kits in the car for redundancy.
About speed ratings; I'd like Y rated tyres since my ego wants its say, 155MPH restrictor-or-not. The car I'm looking at is running 30 or so more horses, the owner says, from the very first owner before him. Probably an aggressive remap and nothing more, and hopefully not a cause for concern. Would W rated tyres make more sense though, since they'll warm up faster?
Is W even the next speed rating down from Y? lol. If I go ahead with the purchase, against my family's wishes, I'll probably end up getting the BMW Performance Power Kit, standard on the 35is, which gives better cooling via a bigger, faster fan and secondary water radiator, probably running on a seperate thermostat. The 35is bigger intercooler is definitely a good idea too if I can find one. Temperatures here can surpass 40 Celcius in high Summer. Not as pleasant as it sounds. The car's sun-reflective seats and steering wheel would be a God-send.
Is W even the next speed rating down from Y? lol. If I go ahead with the purchase, against my family's wishes, I'll probably end up getting the BMW Performance Power Kit, standard on the 35is, which gives better cooling via a bigger, faster fan and secondary water radiator, probably running on a seperate thermostat. The 35is bigger intercooler is definitely a good idea too if I can find one. Temperatures here can surpass 40 Celcius in high Summer. Not as pleasant as it sounds. The car's sun-reflective seats and steering wheel would be a God-send.
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