Bigger the wheels - Worse the handling ?

[belfastfumanchu 0]

I hear that the bigger size wheels you have on your car then the worse the handling will be.

In particular i hear that 18 - 19inch ones would considerably make any car (corrado included) not handle as well as a car with say 16inch wheels

 

My question simply is, is this true....cos i hadn't heard about it until a friend mentioned it.

[jedi-knight83 0]

yup. not only will anything above 17" handle like a dog, it will mess up the gearing and you'll never get the same driving experience again...

 

stick with 16" or 17"

 

the corrado looks pants on anything about 17" anyway IMO

[dr_mat 0]

There's many reasons..

You alter the rotational inertia of the wheel, thereby stunting your acceleration significantly.

You alter the rolling radius (particularly with 18/19!!) wheels slightly, stunting the acceleration further.

If you choose wider wheels you actually increase the rolling resistance of the car AND the wind resistance, thereby dropping your top speed..

You alter the suspension geometry..

Typically the car is lowered at the same time, and this brings about all kinds of other compromises that need to be configured out of the equation. If the car gets lowered you should definitely do cast/camber/tracking, and adjust the rear brake bias adjuster to compensate.

One thing you generally *do* do with bigger wheels is sharpen the responses, because you have to run rubber-band like very low profile tyres to make them fit in the arches. This gives you stiffer sidewalls which results in sharper handling, but enormous transmission of bumps etc to the cabin..

 

At least, that's how I understand it.. :)

[belfastfumanchu 0]

I learn something new everyday since i got into cars

 

Im also suprised to hear it stunts acceleration.... I'll defo be sticking to 16's it looks then. Good job too as theyre cheaper.

[jedi-knight83 0]

Im also suprised to hear it stunts acceleration

 

this actually depends on a few things...see if you increase the actual size of the wheel, you just get lower profile tyres to compensate..so the rolling radius stays the same and therefore the acceleration / gearing / top end would not be affected. if you get a wheel bigger than 17" though and then add a tyre...even with a rubber band type low profile tyre the rolling radius is going to be bigger than standard...thus giving you speed / acceperation issues..

 

ok thats that...

 

but, if you get a 16" wheel that is much much heavier than your 15", even if you get lower profile tyres to keep the rolling radius the same..you will still have slower acceleration as the car is having to spin heavier wheels to get going :roll:

 

if you can find some nice lightweight wheels to suit the corrado your laughing...if not... well you either going slower than us, or sticking to standard 8)

[GazzaG60 0]

bbs RCs are pretty light.

 

with my old 17" on it felt slower and less responsive on the turn than with the 15"

 

with the RC itt feels much the same as with the 15" bbs standard rims except its more stable and better gripping with the RC due to the tyre wall/more surface area combo as state above

[jedi-knight83 0]

and adjust the rear brake bias adjuster to compensate.

 

Why?

[belfastfumanchu 0]

bbs RC's you say Gazza - interesting interesting - i might have a look at them.

[Kevin Bacon 5]

Because it stops the rear brakes locking up. The rear biasing valve is there to compensate for the rear axle moving up down, whether that be through having 2 heavy mates in the back or simply going over bumps. If it weren't there, the rear tyres would light up all the time. When you lower the car, it assumes the car is laden and therefore allows more biasing to the rear brakes which is not a good thing mid bend.

[Henny 0]

and adjust the rear brake bias adjuster to compensate.

 

Why?

 

When you lower your car, the brake bias valve thinks that the car has a lot of weight in the back, so it allows more brake pressure to the rear brakes... This can make the rear end skittish, and if your ABS isn't working, it can make the rear end lock up way too easily... If you adjust the valve once you've lowered your car, it then knows that it's supposed to be that low and isn't loaded up, so it'll allow the correct amount of braking force to the rear calipers... 8)

 

IIRC, it's only 1 bolt that you need to undo to adjust the compensator... 8)

[dr_mat 0]

In answer to the two questions here:

The mass of the wheel is not so important as how FAR that mass is from the centre. Any wheel has the majority of it's mass in the rim, not the spokes. So the rotational force required to turn that wheel is more or less proportional to the diameter of the wheel (multiplied by the mass). So even if you fit a larger wheel that is the SAME weight as a smaller one, it still requires more rotational force to turn it, which is force that would otherwise have been applied to the road and used to accelerate your car.

Secondly - the rear brake bias valve uses the position of the rear axle to decide how much weight is on the back wheels, and sends more or less braking force to the back wheels accordingly. If you drop the springs, you trick the brake bias valve into thinking there's permanently more weight on the back wheels, and you may well find it locking the back end up when you wouldn't expect. Which is bad.

HTH.

[dr_mat 0]

Ahem. Which Henny just said...

[Henny 0]

Ahem, and Kev just before too... :roll: :lol:

[jedi-knight83 0]

Which Henny just said...

 

and kev actually :wink:

 

is there more info on this brake bias valve then?? i.e where is it. how much to turn the screw etc

[dr_mat 0]

I type too slow.

Well actually, in my defence, I typed twice as many words...

[Kevin Bacon 5]

LOL....battle of the posters :lol:

 

You rarely need to touch the biasing valve Jedi. It has a certain amount tolerance built in because the rear axle is bumping up and down the whole time you drive the car. The general consensus if you lower to -30 max, you don't need to touch the bias valve, I certainly never have with that amount of lowering, with no ill effects.

 

Go any lower than that and it's wise to reset the valve. I think all you do is release a nut to slacken the spring tension and then do it up again in the car's neutral position. Climb under the car by the nearside rear wheel, feel to the back of the rear axle and you'll see the valve tucked up in the corner of it. Grab the spring and arm and wobble them. If they're slack, you don't need to do anything. If the spring is tight, it needs resetting.

 

K

[cheesy 0]

To some people this will sound strange

 

since i have fitted my 18's the car handles loads better than my 17's did

and the ride is as good if not better. Acceleration is better. massive undergearing at speed.

 

One reason i can think of is the wheels are lighter than my old 17's

[Sandy 0]

Just increase the power of your engine with a few engine mods to compensate

 

Sandy

[dr_mat 0]

The new wheels would need to be less than 17/18ths of the weight of your original ones for there to be an improvement in the acceleration.

You sure you haven't just got heavier shoes on? ;)

[cheesy 0]

Just increase the power of your engine with a few engine mods to compensate

 

Sandy

 

Thats what i'm doing

Been speaking to Vince at Stealth this morning 8)

 

The new wheels would need to be less than 17/18ths of the weight of your original ones for there to be an improvement in the acceleration.

You sure you haven't just got heavier shoes on?

 

Heavier shoes, hehe :wink:

[MikeVR6 0]

Belfastfumanchu

 

When I was buying the Speedline wheels that are on your car, I did lots of research into this topic.

Having had 17's on my previous car, I knew how badly they transmitted bumps etc into the cabin.

I found 16's to be the best compromise between looks and handling.

With 205/45/R16 tyres they're nearly the same Rolling Radius as the original 15's. So gearing and top speed are only slightly affected.

 

As for the weight of the wheel, Speedlines are an expensive wheel due largely to the fact they are lightweight whilst retaining the strength of wheels made from heavier alloy.

They're standard equipment on Subarus and Ferraris IIRC.

 

By comparison, the 16" BBS RDs I've just fitted to my VR6 cost £700 with Toyo Proxies.

This was an extremely good price.

The Speedlines were £700 new with cheapy tyres.

I priced similar wheels for the VR with Toyo's last week and they came to £950!

 

Think long and hard before changing the wheels and if you do, go for BBS or OZ wheels.

Anything that doesn't cost around £700 or more isn't worth looking at.

 

My 2p's worth :wink:

Mike

[dinkus 10]

Personally I'd rather spend the £700 on something that would make my car handle/perform better than on something that will slow it down, but I guess form over function and all that... :D

[MADDUB 0]

hm i ant to sure but i will soon fined out my new wheels are 10/18 on front and 13/18 on the back 3 pieas split rims from image :-P

[belfastfumanchu 0]

Mike I'll not be buying any wheels for a while yet. Merely enquiring !