458 Italia max front tyre width using aftermarket rims?

Hi guys

A friend of mine, who's not a member here unfortunately, and I talked tracking cars last night, and started discussing tyre width. He asked me if I knew what's the widest tyre you can fit on either a 19" or 20" front wheel of a 458. We're of course talking aftermarket wheels, and I do know of guys running 265/30R20, 265/35R19 and 265/30R19.

Question is, does anyone know if any of these sizes will fit without rubbing and not stick out past the fenders? Of course the correct offset is needed as well as rims with a width of at least 9" for the 275 section tyres and 9.5" for the 285. We both think these widths will compliment 325, 335 and 345 section rears quite well.

275/30R20
285/30R20
275/30R19
285/30R19

Thanks in advance everyone.

 

I'm very certain I'm not going to confuse anything. As long as I keep the front to rear difference within reason I can do it. The 275/30R20 tyres are 26.5" (OE dia) in diameter, the 285/30R20 is 26.8" That's a difference that works. I run 245/35R20 on the front of our 458 Spider. Those are also 26.8" in diameter.

If you read through my posts, I think you'll find I know my tyres, diameters, ABS issues and so forth. As long as you keep the front to rear diameter bias within reason compared to OE, it can work. If I or my friend were to run a 19" setup, it would be a pure track setup with an overall smaller diameter. You have to remember that the ABS wheel speed sensor has no idea of how wide the tyres are or how large the overall diameter is - it works on the principal of the front and rear wheel rpm in relation to each other. And also, if you increase both the front and rear width, you'll also keep the car from understerring and pushing, unlike if you install very wide rears with stock width fronts.

The tyres to combine that should work would be these:

Note that OE diameter is 26.5" and 28.1" for the MPSS and that's a front to rear diameter bias of 6.039%.

275/30R20 and 335/30R20 26.5" and 28.0" diameter. 5.56% bias
285/30R20 and 345/30R20 26.8" and 28.2" diameter. 5.56% bias
265/30R19 and 325/30R19 25.3" and 26.7" diameter. 5.56% bias

These are just examples. My point is simply, if you keep the biases in check, you should be fine. This is also why those who try to run the Speicale tyres on their Italias, have issues. The diameter bias is only 1.5%.

 

I actually did ask. They only talked about their own wheels and didn't offer up any specifics other tan they use 255's in the front. And I'm not into heavy wagon sized bling bling rims and need specifics on wider tyres

Actually OZ makes a nice light forged 19" specifically for the 458. And generally, most good 19" wheels along with the Cali/Cali T rims will fit. The FF, F12 and 458 Italia/Spider can all run 19" rims.

Forgeline can make their GA1R Open fit in an 18" - it's quite popular with those who track Corvette ZR1's. It's all about the rim barrel design.

 

The reason why I mention the ABS, is because what get's confused when changing front to rear diameter bias, is the ABS wheel speed sensors. The 458 stock wheels have a front to rear diameter difference of 6.25%. As long as you keep it like that or close to it, the overall diameter does not matter as the wheels keep the correct RPMs in relation to each other.

What I like about the idea of running 19" wheels with a low profile tyre, is that it will do three good things.

1 The weight of the tyre carcass and tread is less, and further in on the overall circumference. Removing weight off and devreasing the outer most circumference, is a huge plus in terms of how the car handles, steers, accelerates and breaks.
2: If the overall diameter is say 1½ inch less, that will lover the car by 3/4" and thus the CG. There will also be less air pressure build-up in the wheel wells and more air will go over the car, rather than under. Both should have a positive impact on downforce.
3: The smaller diameter will act like a shorter final drive ratio which will help acceleration.

 

This is exactly why if I change anything, I won't change the relationship between the front and rear tyre diameter. If I don't, there's no errors. As you know, the front to rear wheel speed is the basis of the ESC/ABS system. As long as the system works without errors and irregularities, the systems should work normally and detect loss of grip by changes in wheel speed. Besides that, as long as the tyres are the same diameter on both sides, I can't see why the e-diff should have any issues. It's all about wheel speed and I can't for the life of me see how there could be any issues if the "relationships" front to rear and side to side are in order.

Am I missing something?