Z4MC Tire Sizing Questions

[U235]

I need new tires on my Z4MC quite badly. Everyone says I can run 275s without problem, but despite numerous searches, I've not been able to find consensus on whether 275/35 or 275/40 is run. Either way, it's about 0.8 mph @ 60 off. I'm not sure which one people are running.

Also, what is the recommended aspect for 245s in the front?

Unfortunately, my front tires still have a tons of tread so I'll only replace the rear set and will run Conti + Whatever I get in the back until the fronts need replacing. I don't really mind that, but I know it's less than ideal.

While on the topic, any model recommendations would be appreciated. PS2s and Dunlop Star Specs seem to come recommended often. I want a great performing tire, but wouldn't mind sacrificing a slight bit of performance for noise and treadwarae.

Thanks,
Brian

[U235]

Sorry, it seems 275/35/18 and 255/40/18 is the size.

I worry if I put 275s on the back with my 235s up front that it'll understeer bad and be a radical change for the car. I don't want to replace all 4 since the fronts have a lot of tread. I may go 265/40, just need to choose a tire.

[MVF4Rrider]

The Z4 M speedo is 3 mph off at 68 mph. Go with OEM sizes. Sure you can't go for all 4? It's a $50K sports car for Pete's sake!!! Just get PS2s instead of the crap Contis if you care about grip.

[U235]

Originally Posted by MVF4Rrider

The Z4 M speedo is 3 mph off at 68 mph. Go with OEM sizes. Sure you can't go for all 4? It's a $50K sports car for Pete's sake!!! Just get PS2s instead of the crap Contis if you care about grip.

First, there are plenty of great alternatives to PS2s. I've always preferred Bridgestone to Michelin, just personal preference. I'm considering a handful of tires including the PS2, but so far it's down on the list (RE960A Pole Positions, Dunlop Star Tecs are both higher on my list). Also, regardless of the expense of the car, throwing away two perfectly good tires seems wasteful and unnecessary. I don't track this vehicle and it's primary duty is to get me from point a to b, albeit a bit faster than the rest of the pack and with a little bit more purpose.

Also, within 10-15k miles, I will be back at sqaure-1 with poorly matched tires (75% tread up front, 15% in the back, etc.). With staggered setups, you'll only have a matched set for a limited time with 4 new tires. This is my 4th vehicle with staggered setups and I've always replaced rears 1x year and fronts 1x/2 years. It's worked for me.

As far as the speedo off, are you saying that by default/stock it's 3mph? I show a less than 1mph difference at 60mph with the difference between 255/40/18 and 275/35/18.

Thanks for your feedback.

[chickdr]

Originally Posted by U235

First, there are plenty of great alternatives to PS2s. I've always preferred Bridgestone to Michelin, just personal preference. I'm considering a handful of tires including the PS2, but so far it's down on the list (RE960A Pole Positions, Dunlop Star Tecs are both higher on my list). Also, regardless of the expense of the car, throwing away two perfectly good tires seems wasteful and unnecessary. I don't track this vehicle and it's primary duty is to get me from point a to b, albeit a bit faster than the rest of the pack and with a little bit more purpose.

Also, within 10-15k miles, I will be back at sqaure-1 with poorly matched tires (75% tread up front, 15% in the back, etc.). With staggered setups, you'll only have a matched set for a limited time with 4 new tires. This is my 4th vehicle with staggered setups and I've always replaced rears 1x year and fronts 1x/2 years. It's worked for me.

As far as the speedo off, are you saying that by default/stock it's 3mph? I show a less than 1mph difference at 60mph with the difference between 255/40/18 and 275/35/18.

Thanks for your feedback.

Agreed about the PS2's. There are several good alternatives including the Dunlop Direzza StarSpec/Hankook Ventus K12 Evo and now the Continental ExtremeContact DW which all get excellent reviews. I would also suggest you go with all 4 this time since you are likely switching brands. The stock Conti's are universally maligned and I would be loathe to keep inferior tires on the front of the car. If you pick new tires you are going to stay with you can keep the fronts longer from that point on... I would wait to increase sizes if you aren't going to do all 4 tires.

[U235]

Originally Posted by chickdr

Agreed about the PS2's. There are several good alternatives including the Dunlop Direzza StarSpec/Hankook Ventus K12 Evo and now the Continental ExtremeContact DW which all get excellent reviews. I would also suggest you go with all 4 this time since you are likely switching brands. The stock Conti's are universally maligned and I would be loathe to keep inferior tires on the front of the car. If you pick new tires you are going to stay with you can keep the fronts longer from that point on... I would wait to increase sizes if you aren't going to do all 4 tires.

Funny you said that as I just read good things about the Hankooks and was thinking about those, I can't find a reason not to except that they're Korean and I have nothing against that.

[chickdr]

Originally Posted by U235

Funny you said that as I just read good things about the Hankooks and was thinking about those, I can't find a reason not to except that they're Korean and I have nothing against that.

On the various boards there have been several who have gone with the Hankooks and all have been happy. You should be able to get an entire set for around 6-700 which is a steal.

[AWM3]

BMW speedometers always read higher than the actual speed. You will just have more of the same, only a little bit greater if you reduce the diameter of the tire.

[stubble88]

ive got: 265/35/18 R 245/40/18 F Dunlop Star Specs

Using this setup for AutoCross and daily driving

I wish I had gone 275 now in the rear, but just did what was recommended
but the fronts are maxed
this is on stock suspension

I did some research and thats how I ended up with 265 in the rear.

Dunlops Star specs are #1 according to Tire Rack..

[bosstones]

Anyone here ever tried Goodyear Asymmetrics? Those had really good reviews when they came out. I'm surprised no one has mentioned them here.

Dunlop Star Specs have been well received by some people I know that run them.

[k2pilot]

if you don't drive in rain often i'd also look at the nitto nt-05's, i'm looking at grabbing a pair as my summer/track tires.

[U235]

I went with the Hankooks all the way around. The price/performance can't be beat, and I expect I'll be going through a handful of tires on this car

[monaco_e90]

I've got the star specs in 275/245, zero complaints. I happily threw away contis on the front that has 6 months more more left in 'em. Good riddance to bad garbage....I didn't realize how bad they were till I got the Star Specs on. If you wanna cheap out and have a goofy, super staggered setup to save $50-$100 (the remaining value in your fronts, if you don't count that they sucked when brand new) you might as well not have the car.

The star specs looks really nice on the car, too.

Edit: didn't see your last post, that's a good way to go, as well.

[U235]

Yeah the Hankooks look good as well, except they say Hankook, LOL. The 275s look more serious from the rear. I'm really happy with the ride and quietness of these tires. Due to rain and a lot of travel, I haven't put many miles on them yet and haven't gone on a serious drive with them.

I did notice that my car slightly pulls to the left now. I heard it's normal on these cars (from another forum) that after a tire change it takes some time for things to settle in. When I get home from my current round of travel, I'll take it in for alignment just for peace of mind.

For the price I paid $820 installed for these tires, I'm quite happy with all aspects of it. I'm still able to easily get the rear end squirlly through corners though. I actually think my bald and slightly steel belted Conti's had a little bit more hook, but that'd be expected considering they were basically slicks and had more surface contact