Rolling diameter/circumference clarification - understanding

[EthanolTurbo]

Here's a good link, the author is a very successful time attack and race driver.

https://motoiq.com/how-to-properly-s...r-performance/

Basically if you're doing a setup for street, it really is best to just stick with PS4s or similar and the 225/255 or 235/265 split. You do not need wider than that on a 9" / 10" wheel setup and you'll be losing performance.

A052s are way overkill for a street tire. But if you really want what is in reality, a track day tire, then do yourself a favor and do not get 245/275s. They will be way too wide.

Lifespan is also trash on the A052 lol. I would take a look at the AD09 which is supposed to have almost the same grip level but with much improved lifespan.

Agreed. Mega sticky track ready tires are pointless on the street and make you a worse driver. And they usually ride/sound like shit. The limits are so low on the street that there's not much advantage and many disadvantages.

Also, Billy J is a really great driver with a lot of knowledge and advice to give out.

[Tbonem3]

Here's a good link, the author is a very successful time attack and race driver.

https://motoiq.com/how-to-properly-s...r-performance/

Basically if you're doing a setup for street, it really is best to just stick with PS4s or similar and the 225/255 or 235/265 split. You do not need wider than that on a 9" / 10" wheel setup and you'll be losing performance.

A052s are way overkill for a street tire. But if you really want what is in reality, a track day tire, then do yourself a favor and do not get 245/275s. They will be way too wide.

Lifespan is also trash on the A052 lol. I would take a look at the AD09 which is supposed to have almost the same grip level but with much improved lifespan.

Ya thanks. For a052 or any 100 - 200tw, I don't care about wear, this is just for fun and money is not a concern. With A052, I'd be doing 235/265 (they don't make a 275 anyway) or if I go 9.5/10, then I'd do 255/265 probably. For me, the biggest allure of the a052 besides best dry grip in class (basically) is the weight. Most 200tw are a good 2-3lbs heavier per tire! AD09 are 2 lbs heavier as well. Cup 2s are light as well. Ps4s are fairly light.

Mostly, I know ps4s is good enough, but it's those moments where they're not that I'm thinking about, otherwise, I'd leave things be.

[9kracing]

Why doesn't anyone ever consider the Firehawk Indy 500?

They're just rebranded Potenza RE003s for the US market, and for the price I don't think there's a better street tire.

[Nate047]

For sure, the A052 is a great tire. Mine lasted a couple track days and they were done.

[bavarian3]

Bumping this as I'm picking tires for my 18x9.5 front 10.5 rear setup. I've read the tire fitment thread. 245/40 PS4 on 9.5" wheel look stretched and bulky. Was thinking of running 265/35 front 275/35 rear.

I'm trying to understand as a RWD car why DSC cares about a slightly smaller rolling diameter in the front. Speedometer and other performance changes are certain, but does anyone have actual first hand experience of the DSC behavior change doing something like this?

I'm considering purchasing 2 rear 275/35, mounting em up to the 10.5" wheels then throwing my OE 18x9 on the front which currently have 255/35 on. Drive it around and see what behavior I get from DSC.

[bmwfnatic]

I'm trying to understand as a RWD car why DSC cares about a slightly smaller rolling diameter in the front. Speedometer and other performance changes are certain, but does anyone have actual first hand experience of the DSC behavior change doing something like this?

I'm considering purchasing 2 rear 275/35, mounting em up to the 10.5" wheels then throwing my OE 18x9 on the front which currently have 255/35 on. Drive it around and see what behavior I get from DSC.

DSC doesn’t work if it is seeing a different front and rear wheel speed, I am not sure if the limit is documented anywhere but I know at around 4-5% it considers it too much.

265/35/18 and 275/35/18 are around 1% different.
255/35/18 and 255/35/18 are around 2% different.

So I believe both those combos will be fine.

[bavarian3]

DSC doesn’t work if it is seeing a different front and rear wheel speed, I am not sure if the limit is documented anywhere but I know at around 4-5% it considers it too much.

265/35/18 and 275/35/18 are around 1% different.
255/35/18 and 255/35/18 are around 2% different.

So I believe both those combos will be fine.

Thanks for the input.

I double checked my current setup(from previous owner) and it's actually sitting on 225/45 front 245/40 rear. I hadn't payed attention to it since they are planned to come off, but I have noticed no effects of having a larger circumference front tire. Granted, I haven't ripped on the car too much, but I'll have to break some traction to see if I notice anything odd.

[Obioban]

The closer you can get to equal rolling diameter, the less annoying DSC is. At 1-2% it wont' do the thing where it never recovers until you disable the system, but it's still a bit more annoying.