18" Alloys

[amberforce]

Are there any problems with putting 18" alloys on a 450 Chimaera (year 2000)? The possible tyres that are being offered as part of the wheel and tyre deal are 215x35x18 all round or 225x35x18 all round with 4x108 ET15, which I assume is the offset.
Any advice would be greatly appreciated, as I don't want to spend £700-800, and then find I have to make other alterations.

[tvrbob]

Yes it makes the car look great but the ride is destroyed. Reducing sidewall height increases bump steer and tramlining. It also makes it handle like a dog on undulating country roads. 17" is as big as you should go, anything bigger and you're entering the max power zone, looks great but drives like sh1t

[adavy]

The offset is miles out. Don't touch them!

[Full SP]

tvrbob said:

Yes it makes the car look great but the ride is destroyed. Reducing sidewall height increases bump steer and tramlining. It also makes it handle like a dog on undulating country roads. 17" is as big as you should go, anything bigger and you're entering the max power zone, looks great but drives like sh1t

For clarity, we agree that 18s on the front are generally not good for handling and/ or driver comfort, but 18s on the rear are extremely good (we have supplied dozens of SP12s 17F, 18R with 100% satisfaction).

[OscarT]

The offset will depend on the rim width.

[tvrbob]

Full SP said:

For clarity, we agree that 18s on the front are generally not good for handling and/ or driver comfort, but 18s on the rear are extremely good (we have supplied dozens of SP12s 17F, 18R with 100% satisfaction).

No, not extremely good, 18" rears are within what I would define as tolerance. If you drive 18" and 16" rears on the track you will find the 16" are far better in the corners. 18" rears work well on flat roads and are acceptable on country roads, however worse that 16".

The point is that people are not fitting them to make the car drive better; they are fitting them to make the car look better. The message is firmly in that statement.

Edited by tvrbob on Sunday 18th November 13:28

[amberforce]

I agree with the last comment as this will be the main reason why I want to fit them to my car. I am not bothered about high performance and handling as long as it looks good through the summer months.
Does anyone have DARE alloys on their car???

[schueymcfee]

I have 18s on mine and I can confirm that the car rides and handles like a total pudding. It even has AVOs on but to no avail.

Having said that the car looks a thousand times better, not chavvy at all - it's all personal preference and what you want the car for.

[tvrbob]

schueymcfee said:

I have 18s on mine and I can confirm that the car rides and handles like a total pudding.

Thanks for your honesty

[spend]

tvrbob said:

schueymcfee said:

I have 18s on mine and I can confirm that the car rides and handles like a total pudding.

Thanks for your honesty

There are quite likely a few on 15/16"s that are in the same boat Bob Personally think setup and rubber may make larger wheels work, mine was ok on 18" (nowhere near as good as 16&quot, I wanted to be able to swap wheel sets when I wanted but the setups were just too different to be able to do it easily (and tales of buckled 18" spiders put me off - sold them for a nice sum tho)

Dave

[jsr]

I'm looking at getting some new wheels at the moment, mainly to give me greater choice of tyres and also to make the car look more modern. I've photoshopped a few examples and IMO i feel 17" looks too small at the rear. The 17 front and 18 rear look best

However, i am thinking about an 18" front as this would give the option to use the Goodyear Eagle F1 Asymmetric which has been winning tyre tests this year.

My car corners great when the suspension is loaded up, yet ride quality is pretty poor. I have stiffer springs still to fit to my avos and i'm sure it could do with new bushes and a proper geometry setup. I strongly believe the car can be setup to be acceptable on 18's and has the benefit of using the best performance tyres (which dont seem to be available in 17&quot.

[tvrbob]

jsr said:

I strongly believe the car can be setup to be acceptable on 18's and has the benefit of using the best performance tyres (which dont seem to be available in 17&quot.

Not possible. Suspension only works in the up and down direction. Bump steer and tramlining is a function of sideways movement. The tyre tread needs to be able to move from side to side without dragging the rim. All cars suffer from these actions but with most set-ups the ability of the tyre to absorb the side to side drag without transmitting that motion to the wheel rim is what overcomes tramlining and bump steer. If you reduce the sidewall height you also reduce the side to side flexing. This will reduce the amount of sideways movement the tyre can absorb so sideways movement will be transmitted to the rim sooner.

Fit 18" fronts if that's what moves you but don't pretend that your car will perform the same. It won't, it will spoil drivability. You suggest you are doing this to make your car look better, leave it at that.

Edited to add

Another benefit of sidewall flexing is that it provides the progressiveness of under and over steer. If you remove that progressiveness then under and over steer will snap rather than slide. Your chances of rescuing the situation are reduced accordingly. Do it, but do it in the knowledge that the car will change.

Edited by tvrbob on Sunday 18th November 21:51

[amberforce]

So it would seem that the better set-up would be to put 17" on the front and 18" on the rear then?

[tvrbob]

amberforce said:

So it would seem that the better set-up would be to put 17" on the front and 18" on the rear then?

Well that would maximise rim size. 'Better set-up' is not the message I would taking from this. Nobody here has experienced all options, rims sizes and tyre options, so this topic will always be opinion lead, mine included. IMO 16" front is preferred for the 'all rounder' set up, any bigger and you may induce snap understeer on undulating roads. Perhaps you could get away with 17" with a well chosen soft wall tyre if such a tyre exists.

Rear rim size depends on how you use the car and tyre choice. If you want to maximise drivability and track day options you need to think carefully about the compromise between the cars appearance and its handling.

In the end the bigger the rim diameter the softer your choice of tyre side wall needs to be. Don't go for good looking tread patens, go for soft side walls. Rigid side walls and big rims will put you in the hedge every time.

[Filos Hippos]

So if you opt for 17" front and 18" rear what would be the ideal tire size?

SP suggest: 215/40-17 Front and 245/35-18 (max)Rear on there 7x17 and 8x18 rims.

My 2003 LHD 450 was originally on 225/45-16 front and 245/45-16 rear.

So for the fronts:
225/45-16 = 24inch diameter to 215/40-17 = 23.8inch diameter

For the rears:
245/45-16 = 24.7inch diameter to 245/35-18 = 24,8inch diameter.

If I understand correctly, I'dd better opt for a slightly larger sidewall height in order for the car to feel "progressive" in under- and oversteer.

For instance:

Front:
215/45-17 instead of the 215/40-17 which increases the diameter to 24.6inch.(+0.6inch comp. to orig.setup)

Rear:
245/40-18 instead of the 245/35-18 which increases the diameter to 25.7inch.(+1.0inch comp. to orig.setup)

The question is:

A: will this larger tirecombo fit?
B: will it increase the handling compared to the sp setup?
C: is the slightly larger diameter within what is (legally) acceptable?



Thanks in advance for your help and insight. . .

[tvrbob]

I wouldn't suggest increasing the overall diameter.

It's not illegal but it will create an error on the speedo reading and the only reason you would put 18" wheels on is to make the car look better. The low profile tyre is part of the aesthetics of the larger wheel rim look. Putting bigger outer diameter on will compromise the aesthetics of the car so you may as well stick with 17" and maintain the original outer diameter.

[Filos Hippos]

Hi Bob, thanks for your reply.

The size 215/40-17 compared to what was originally fitted does not only decreases the width but also the diameter.

It is ofcours only 225 to 215 and 24 inch to 23.8 but still, ...

So I was wondering if it wouldn't be better to increase slightly rather then decrease.

It's a shame Toyo does not offer 225/40-17, that'dd be ideal in my opinion.

Also I feel that a larger wheel overall (rim+tire) does not compromise the appereance of the car at all.

just a thought. . .

[spend]

You can also get into lots of problems with wheels/tyres fouling the arches / wishbones / bodywork. Not a problem if you want to start tuning your whole suspension....

I don't think I would really want skinny 7" rims or 215 tyres on the front, something a little more buxom would be my aim

Dave

[tvrbob]

spend said:

You can also get into lots of problems with wheels/tyres fouling the arches / wishbones / bodywork.

...also at full lock. I had to fit steering rack end stops to prevent mine from snagging on full lock after fitting 16" fronts with 225's on

[shadowninja]

Not a single picture!