lower profile tires?

dear all i would like to put lower profile tires to further lower the car as i am maxed out on lowering the stock coils and do not want to put aftermarket springs

i would like to put 295/25/20 in the rear and 235/30/20 in the front both pirelli p zeros

i currently have the stock 295/35/20 rears and 235/35/20 fronts

am i assuming correctly that the car will be 29.5mm lower in the back and 11.75mm lower
in the front with the lower profile tires?

also how do you feel about driving with a lower profile 20i tires than the stock 20i ones and, more importantly,
any thoughts about driving with a lower profile tire in the back than in the front?

thx for the input !!

 

Your calculations are correct.

Don't forget to consider the alteration to the vehicle rake this would cause. Lowering the body by over an inch in the rear and less than 1/2" in the front may not look great.

Also, when going to a lower profile tire, the tire sidewall MUST occupy MORE THAN half of the space between the rim edge and the fender edge, otherwise you'll look like you're on rubber bands. Covering 50% of the distance is quite marginal... Look around at some pictures of cars and try measuring that ratio.

 

thanks for info don

 

You will also lower the effective gearing of the car by over 8% which is already fairly short geared. This will translate into 8% less speed in each gear, and correspondingly higher acceleration in each gear. But before you conclude that this will make the car quicker all around, conisder for example that at around 80 mph, you will need to be in 4th gear vs. 3rd.

IMO it is a very large change and should be considered very carefully before going ahead.

 

Altering the car's rake can also negatively affect aerodynamics and handling at speed. I don't think I would change the rake unless I had a lot of experience with ride height adjustments and their effect on handling. It probably wouldn't matter when just boulevard cruising, but it may be dangerous when driving quickly/aggressively. Unfortunately, though, I'm not knowledgeable enough on the subject to properly advise.

I would, at the minimum, get the dealer's opinion.

 

forgive my ignorance noblesse but what is the gearing and how is this affected by lowering the profile of the tires?

 

thanks for the input rob, I realize that lowering the car more at the back than in the front can negatively alter aerodynamics

how about going with 295/30/20 and 235/30/20's? will this also affect gearing?
at least the car will be leveled

 

Honestly you wont lower the car that much and you'll make the wheel gap so big might look funny.

do the math hope this helps so oem tires
235/35/20 26.4" OD
295/35/20 28.1" OD

Now your proposed tires
235/30/20 will be 25.5" OD
295/25/20 will be 25.8" OD

Now fronts original are 26.4 - new 25.5 = .9 that's a circle so then divide by 2 so your car in front will go down .5" approx and you'll also increase wheel well gap .5"

Rear original is 28.1 then new -25.8 = 2.3 difference , so again so then divide by 2 so your rear will go down 1.15 but then your also making your rear gap 1.15 " you will have huge wheel gaps especially in rear

Then you are also affecting the gearing of the car like members said above.

hope this helps

 

the gearing ultimately is the ratio between the RPM of the engine and the forward motion of the car.

if you make the wheels smaller in diameter, the car will travel a smaller distance per rotation of the tires and hence per rotation of the engine.

not a fan of low rider Ferraris here

 

The much shorter sidewalls will also transfer more impact to the suspension, be more likely to damage the wheels from pot-holes, etc.

Any comment on practicality from experience for <35% ratio tires ?

 

i would be keeping the wheels the same diameter (20i) just the profile of the tire
will be lowered, will this still affect gearing?

 

The overall diameter of the tire is part of the overall gearing formula, so yes it would affect gearing.

Lowering the gearing is cool though, it makes the car more responsive with quicker acceleration. It just decreases the effective top speed from 200 mph to 185 mph, which you never use on the street (even most tracks) anyway, unless you are insane......haha

 

ps does this mean that all the owners that are putting larger rims (21i or 22i) on their 458's
are changing the gearing?

how would gearing be affected with larger 21 or 22i rims?

 

The issue is the rolling radius of the tire - how far from the center of the axle to the ground - it doesn't matter if you have 14" or 22" wheels.

 

True it's the overall diameter of the wheel and tire that determines gearing but different diameter wheels and tires vs stock can alter factory gearing.

We did this with Ferrari P 4/5 by Pininfarina to give the car a higher rear ratio which as it gave it (along with wider tire) less need for traction control, faster 0-100 KPH as well a higher VMAX.

 

Thank you for the input Mr. Glickenhaus!!

 

I wouldn't put low profile tires on a 458. First off Ferrari put the tires on the car because they thought it was the best overall tire for various reasons. Second the car looks so good no one is going to notice. Next it will effect the ride which I think is the best of any sports car ever made. I also think it makes the car look cheap Its a Ferrari not a Nissan 370z.

 

still debating in my head wether i should or not....
i may go with 30 profiles as opposed to 35 profiles but then i don't want to have 1/2 more of a gap between tire and fender not to mention all the other considerations....
i might just end up putting some novitec springs so i can lower it a few mm more, i know, i know, im a lowering freak what can i do

 

You got it.

 

One thing to keep in mind. Low profile tires are an issue with potholes but generally they handle a bit better as the height of the sidewall is lower and flexes less. That said the ride quality does become "harsher". In race cars larger diameter wheels also allow fitting larger diameter disks and bigger calipers which improve braking.

Do be careful and keep the car balanced F/R grip wise. Generally slight understeer is safer as when oversteer happens suddenly it's easy to lose the car.

 

I think you will be happily surprised with a good set of lowering springs vs changing the tires. I think your desire to keep the suspension stock is what leads you to not want to mess with the suspension. However, tires are actually a part of your suspension. So you're already making changes. Do it right- do the springs. JMHO.

 

Thank you all for your input!

The car is already very low as it is lowered at the max on the stock coils.

As it sits I have about just 8cm or 3.1i ground clearance, the car is
as low as a 458 challenge race car.

If i go with 30 profile tires instead of the stock 35 profile it would lower the car
another 0.46 inches (1.17 cm) bringing down the clearance at just 6.9cm or 2.7i.

I don't want any damage to the underbody but especially to the rear diffuser fins
as I have scraped the 3 right ones and replaced them already twice.

I'm just really obsessive and I think am splitting hairs at this point with the ride height
question....

Pics of her at current ride height with her girlfriend (it the most recent pic i have as she currently sits albeit not a very good one see the ride height) and two videos of her on the street: should I go any lower, what do you think??


[ame=http://www.youtube.com/watch?v=up0E1fnDR7g]Ferrari 458 Italia maneuvering - YouTube[/ame]
Image Unavailable, Please Login

 

You've already scraped and replaced the rear diffusers twice, and you're still considering going lower? It's your car and your choice, but I think you're already too low.

 

The factor is the overall diameter of the tire, so it all depends on how thin the tires are on those 21s or 22s.

But in general, yes those guys with 21s or 22s have larger overall diameter tire, which fills up the wheelwells to provide that awesome look. But effectively giving it a higher gear ratio, which makes the car less responsive with slower acceleration, but higher Vmax/top speed (compare to stock).

 

If you want my honest opinion:

I am a recovered lowering freak, I absolutely love that slammed/flushed look, I have nothing against modding any cars, Ferrari or not.

With that being said, I think your car the way it sit now, looks fantastic and is perfect, I love it

On the 458, the stock tire size is the best size for the stock wheel's size, both for performance and looks, the front tire sidewall is already very tiny, making it thinner would make your wheels very vulnerable to pothole damages. And even though thinner tires would effectively lower your car, but it would actually make your car look worse from having more empty space in your wheel wells.

Trust me, what you have now is perfect, just enjoy it