WHY do bigger alloys mean worse handling?

[iainh]

Right, tell me if I have this right. I have 15" on my mk2, I like the look of the 17" but, from what I have read on the forum I would say, if you have 17"/18" wheels you have a bumper drive(less air in tyre). 15"/16" you get a more comfortable ride.
Now 1/4 mile doesn't bother me, but the MR2 is bad for letting go going round bends/corners I want a tyre that will grip and give good feel, I want to know when it is about to let go .
So if I have 16" with 195/45 & 225/40 this will feel and grip better than 17" 195/35 & 225/30
I concidered changing the size from 6JJ/7JJ to 7JJ/8JJ 205/235, but from what I have read this would make the steering heavy but the rear grip would be better!!
Any thoughts would be wecome.

Iain

[jonb-]

IMHO the simple answer is go with whatever wheels you like the look of but spend as much as you can on tyres.

The difference in ride quality between 15s and 18s on my old NA wasn't really /that/ apparent as the suspension was rock hard and if hooning it around bedford autodrome was anything to go by, i actually found it much easier to drift on the 18s.

If you're not worried about that final 10th on the track and aren't an idiot on the road i can't see why 7JJ/8JJ 205/235 on 17s would be any worse than another setup with like for like rubber.

The rev1 might have been snappy but i find rev2+ to understeer on the road. If you don't understand when the car is about to slide you should get out on a track (this applies to everyone, not just to you).

[Leon.]

Right, tell me if I have this right. I have 15" on my mk2, I like the look of the 17" but, from what I have read on the forum I would say, if you have 17"/18" wheels you have a bumper drive(less air in tyre). 15"/16" you get a more comfortable ride.
Now 1/4 mile doesn't bother me, but the MR2 is bad for letting go going round bends/corners I want a tyre that will grip and give good feel, I want to know when it is about to let go .
So if I have 16" with 195/45 & 225/40 this will feel and grip better than 17" 195/35 & 225/30
I concidered changing the size from 6JJ/7JJ to 7JJ/8JJ 205/235, but from what I have read this would make the steering heavy but the rear grip would be better!!
Any thoughts would be wecome.

Iain

The profile sizes you suggest are slightly out. With 195 and 225 on 16s you'd need 45 on both to maintain stock rolling radius. On a 17" rim you'd need to be on a 40 profile with 195 and 225, or 205/235.

Re. heavy steering, I don't believe the extra width in 205s or even 215s on the fronts with PAS would make much difference tbh, but it will mean you'll understeer less and depending on what you have on the rears, might bring it more neutral or even give a bit of oversteer.

With increased rear grip you will lose grip more suddenly and with less notice but you can get good progressive tyres to help you out with that such as Goodyear F1s.

FWIW a lot of people on here run 215/40/17 and 245/40/17 or there abouts. Obviously you'll need 7 and 8j rims minimum for this setup though.

HTH

[vishpish]

can i just ask, is it totally crazy to go for 17s on a rev1 mk2 na with no PAS that comes on 14's standard? or would it be manageable if indeed one had to make sacrifices for the look(which id be quite willing to do)

[DARRYN]

If handling's not an issue then you can fit the same wheels on a rev 1 as any other so you can have up to 18's realisticly . But it will be a bit heavy to park etc. But exercise is good

[turbokev]

I personally prefer big wheels,i like the handling characteristics,they may break away sharper but i find smaller wheels with higher profile tyres have a whippy feel to them,the flexy sidewalls seem to make the car feel unstable like a spring effect,whereas very low profile tyres are rigid.I find u can feel the breakaway point better due to their stiffer sidewalls rather than high profile tyres which have their own damping effect and dullen any road feel.Modern performance cars are using lower profiles than they used to,why would this be if it had a negative effect on handling?
Spose in the end tho its how u like ur car to feel thats important eh

[Quigonjay]

a rear wheel drive, mid engined sports car handles a bit different to a vw golf mate

[turbokev]

My rallye was 4wd with a 280bhp 20v turbo engine but iv driven mid engined rear wheel drive,front engine rear wheel drive etc etc all the combinations and i still personally prefer the stiff sidewalls of a low profile tyre.Ask yourself this why do all the ferrari's,porsche's etc etc use large wheels with low profile tyre's?
I dont think there's any perfect set up for handling as road conditions vary low profiles,big wheels n hard suspension suit dry smooth roads but high profiles soft suspension suit wet rough roads,its about compromise,horses for courses.As they say....you pay your money,you take your choice

[Leon.]

My rallye was 4wd with a 280bhp 20v turbo engine but iv driven mid engined rear wheel drive,front engine rear wheel drive etc etc all the combinations and i still personally prefer the stiff sidewalls of a low profile tyre.Ask yourself this why do all the ferrari's,porsche's etc etc use large wheels with low profile tyre's?
I dont think there's any perfect set up for handling as road conditions vary low profiles,big wheels n hard suspension suit dry smooth roads but high profiles soft suspension suit wet rough roads,its about compromise,horses for courses.As they say....you pay your money,you take your choice

Did you read the whole thread? The answer is within.

Fashions, styles change. High profile tyres on mainstream cars is out and low profile is in and has been for a few years now - basic models of hatchback/saloon still come with high profile to make the more expensive models more desirable.

Suspension/handling is not just about struts and springs but everything that flexes too. The MR2's suspension was designed taking account of high profle tyres. Cars that have low profile tyres as standard would have had their suspension designed accordingly.

[turbokev]

Thats not neccessarily true,the basic design of modern car suspension has changed very little over the years.Manufacturers don't redesign the whole suspension for their higher performance models they usually just change spring and damper rates to suit,they dont redesign it to suit a certain tyre profile.The handling set up and suspension set up of any vehicle is not a perfect art,just look at motorsport teams thay have the best equipment,technology and expertise at their disposal and yet they still manage to xxxx it up from 1 race to another where even minor changes make a difference.So trying to say that a mass produced road car has had its chassis set up perfectly for every road condition,tyre type,weight load etc etc etc etc,its just not possible with that many variables,road suspension is a compromise for handling,safety and manufacturing costs,otherwise we'd all be driving round in perfect cars.

[Quigonjay]

.Ask yourself this why do all the ferrari's,porsche's etc etc use large wheels with low profile tyre's?

so they can fit huge brakes

[Harry]

I personally prefer big wheels,i like the handling characteristics,they may break away sharper but i find smaller wheels with higher profile tyres have a whippy feel to them,the flexy sidewalls seem to make the car feel unstable like a spring effect,whereas very low profile tyres are rigid.I find u can feel the breakaway point better due to their stiffer sidewalls rather than high profile tyres which have their own damping effect and dullen any road feel.Modern performance cars are using lower profiles than they used to,why would this be if it had a negative effect on handling?
Spose in the end tho its how u like ur car to feel thats important eh

This is true and find the same combinations i have tried mostly on Japanese lightweight split rims full trd/tein racing suspension

7&8" wide 16" volks rays with 20mm odd factory hubcentric spacers
205-50-16-225-50-16...as turbokev says...bouncy unstable bit more comfort fair wet performance...Michelin pilot sport most expensive good
cornering grip

7&8" wide 16" enkei deepdish with 20mm odd factory hubcentric spacers
215-40-16-225-45-16...spot on steering grip lower front raised rear end more rubber is perfect all round in every way...cane it...grb451 Falken
directional excellent wet dry perfect balance makes everything work
how the mr2 likes to.

7,5&8.5" wide 17" gold advan rg circuit magnesium type metal alloy compound material?...this metal compound of rim made it very very hard and very circuit feel excellent handling made the teins work for their money but kept all suspension parts on the case...225-35-17-245-35-17
Falken grb451...here the wide low profile tyre n rims creates a wider track
very very stable n flat a bit less fun than above combination hard precise
no nonsense pro. drive...manic response...all good.

8&9" wide 17/18" enkei split rims...lovely soft feel perfect speed nearly
off gps true speed so lost the over reading from speedo...this light weight
metal material makes a softer ride and is just perfect booting it through
a long sweeping roundabout feels right on it but possible feels slighly taller
than the cheeky 16's above but the wide track keeps the balance flat and
perfect awesome grip n stability...225-35-17-245-35-18...grb451 Falkens.

Never driven on stock rims not interested.

Teins ha coilovers set low with 10/16 rear rebound stiffness front 6/16
spring rate from factory front 4kg-rear-8kg
Tyre pressure front 32-33 rear33-34
4 wheel laser full suspension geometry set up fast road as per mr2 settings being fairly neutral not over set per say Jonb track where tyres
are chewed but grip enhanced.

[skinthespin]

Manufacturers fit low profile tyres to large wheels for styling mostly, and thats all there is to it, why are half the people on here wanting to fit bigger wheels anyway? For the looks of course. Sure you can get bigger brakes inside but for 99% of driving you could get away with smaller discs, plus you would have reduced inertia and unsprung mass because of the smaller disc so you have better handling. As an engineer you have a much better chance of having a good handling/riding car with smaller wheels and discs, as a purchaser for a company its much cheaper to put on smaller wheels and discs but this is over ruled (rightly?) by the marketing departments and the stylists.

It is testament to all the engineers out there that can make a car ride well on low profile tyres.

Manufatcurers do pretty much redesign the suspension on each model too, but you dont do a complete tear up, you build on what you already know as its safer to do that, the cost to a manufacturer to get it wrong is huge so what you do is just move things on a small step from previous and make sure you get it right, its called evolution and its less risky and cheaper than revolution.

Styling has such a big influence on things these days to the point tyre companies employ stylists to design tread patterns on tyres, how many people on here have picked one tyre over another because it looks cool?

Also it must be remembered that handling is subjective, some people like the way a car behaves on low profile tyres others dont, but I suspect the same driver in the same car will lap a track quicker on a tyre that has equal grip but is more predictable.

[Mike 'MR2' McHugh]

Ive recently put 17's on mine, the only differenes i have found are the steering is a little heavier doing manouvres but at higher speed feels more solid and stable. The handling feels fine but i think lowering is on order to stiffin it back up.

[Harry]

[quote="Mike 'MR2' McHugh"]Ive recently put 17's on mine, the only differenes i have found are the steering is a little heavier doing manouvres but at higher speed feels more solid and stable.

Yes also find this

[nicedude1976]

a lot depends on a tyre type, some are very stiff and other not, it can often be more than difference between 15 and 16 inch alloys...

[Lauren]

Ive recently put 17's on mine, the only differenes i have found are the steering is a little heavier doing manouvres but at higher speed feels more solid and stable. The handling feels fine but i think lowering is on order to stiffin it back up.

It will do until you reach the limits of adhesion at which point the 17s though having a far higher mechanical grip, this grip will drop off quicker because of a lower profile and stiffer sidewall. This means that when it does let go you had better be quick to catch it!

[ryan]

FWIW I feel far more confident with std 15 inch wheels and tyres than the lower profile tyre 17" combo.
My rear tyres have seen better days, but twice now in spirited wet weather driving i've managed the catch and deal with an oversteer moment whcih i'm not sure I would have caught (due to lack of warning) on 17 inch rims.

[UniSol]

I've got 18s on my Rev3 GT-S, handles great though I could do with more weight on the front wheels!. I've had Toyota do alignment and camber calibrations and checks.

[Lauren]

I've got 18s on my Rev3 GT-S, handles great though I could do with more weight on the front wheels!. I've had Toyota do alignment and camber calibrations and checks.

I think you may be confusing roadholding with handling, they really are two different things.