17" or 18" Wheels on a slim body

[Dekker]

Hi,
I have a 1993 C4 Cab and want to upgrade the wheels.
What is the max width wheels for a slimline body?

Also has anyone experience of using 18's and what are the pitfalls?
I assume ride will be harder as the tyre profile will be smaller.

Any comments appreciated, David.

 

[Dave Wilkinson]

David,

In terms of width I'm pretty sure you'll find that 8.5J in the front and 10J in the rear are the most you'll get away with - as long as the offsets are right. Fronts need to be around ET52, rears ET47. This doesn't leave a huge amount of space. Max tyre size is generally 225 (F) and 265 (R) although some have pushed the rears to 275. It does depend on the make of tyre.

18's, as I'm sure you know, are not officially approved, yet many - including me - have them fitted. Lower profile tyres means a slightly harsher ride and, perhaps, a greater tendency to "tramline". The benefits include less "squish" on the sidewalls and hence a little more direct steering. Tyres are more expensive though!!

Regards

Dave

 

[deutschland dobson]

Im running 18's on the C4. Ive got 8.5" upfront (225 tyres) with a 10" rear (265 tyres). Offsets are 52 all round. Its tight on the back, but fits (just).

The ride is harder, due to lower profile tyres, and tram-lining is an issue when moving up to larger wheels. Avoid the slow lane of the motorway!

Chris

 

[johncolt]

On my 911 964 I have Turbo Twist wheels with :-
Dunlop 225/40ZR18 tyres with ET 52 offset on the front and,
Dunlop 265/35 ZR18 tyres with ET 47 offset on the rear.
There are no fit problems and they fill the wheel arches well, but the ride is a little bit harsh.

A friend has a 911 968, also with Turbo Twist wheels with :-
Pirelli P Zero 250/50 ZR17 tyres on the front and,
Pirelli P Zero 255/50ZR17 tyres on the back

I don't know what is the offset of these wheels, but I think my car looks marginally better with the larger wheels but, as I would prefrer a bit more comfort rather than ultimate road-holding, I am looking to change my wheels/tyre set-up for 17" Turbo Twists if I can do so without great expense.

 

[l.chadburn]

HI there

I have a 1992 cab and run 18" wheels without any spacers.
The front end is lowered, the rear will be lowered within the next 2 week.

The fronts are 225/40/zr18 and
the rears are 265/35/zr18 Pirelli P Zero's.

As the other guys say the ride is harder, there is also some restriction when on full lock (i.e 3 point turn)

Could someone please explain tram-lining please?

regards lee

 

[l.chadburn]

here is a pic of mine

lee

 

[johncolt]

Tramlining is the tendency to follow wear grooves in the road, usually caused by heavy lorry wheels

 

[911kev]

I run 18's too and have no problems ;

 

[Dave Wilkinson]

ORIGINAL: l.chadburn

Could someone please explain tram-lining please?

As John said, it's the tendency to follow grooves in the road. It's largely caused by the reduced "squish" of the lower profile tyres. Tyres with a greater aspect ratio have more "give" in the sidewalls so the tendency for the tread to follow the road surface is largely negated by the sidewall deformation so the wheel will tend to run true. With lower profile tyres there is much less "give" in the sidewall - designed to give the tyre more direct steering and less deformation in cornering - and the consequence of that is the more direct relationship between tread and wheel.

Regards

Dave

 

[Dekker]

Thanks very much for all your info' and advice guys, much appreciated.

I recently upgraded my suspension to H&R greens with Bilstein HD's and set the ride height to RS +5mm but it's a bit of a tooth rattler on our poor roads, OK on motorways though.
So I'm going to try RS +10 and see if that improves. I like the look of the car when it's lowered so there has to be a compromise between looks and performance.
I will also try lowering the tyre pressures, I understand that the 17" Cups I'm using at the moment are supposed to be at 36psi all round but have read that some run the fronts at 32, so I'll see how that affects handling.

So the 18" I'm going to rule out, for the moment as they would exasperate the hardness of the ride. Pity as I can get them cheaper than I can the equivalent 17's at Design911.

I know Dave's yellow peril has turbo body so I'm surprised that the rears will go to 10J on a narrow body, I know that RS uses 9J according to PET. So that's good news in being able to source other types upto 10J.

Thanks for the photo Lee, it looks great.

Also Kevin, great looking car, is that a turbo body? and those wheels look like Cup 2's with polished rims??

So what tyre pressures do you guys use on those 18's?

 

[deutschland dobson]

Forgot to mention im not using spacers and mine is lowered c.-30mm


Chris

 

[l.chadburn]

Nice looking motor chris.

lee

 

[mr pg]

ORIGINAL: Dekker

Thanks very much for all your info' and advice guys, much appreciated.

I recently upgraded my suspension to H&R greens with Bilstein HD's and set the ride height to RS +5mm but it's a bit of a tooth rattler on our poor roads, OK on motorways though.
So I'm going to try RS +10 and see if that improves. I like the look of the car when it's lowered so there has to be a compromise between looks and performance.
I will also try lowering the tyre pressures, I understand that the 17" Cups I'm using at the moment are supposed to be at 36psi all round but have read that some run the fronts at 32, so I'll see how that affects handling.

So the 18" I'm going to rule out, for the moment as they would exasperate the hardness of the ride. Pity as I can get them cheaper than I can the equivalent 17's at Design911.

I know Dave's yellow peril has turbo body so I'm surprised that the rears will go to 10J on a narrow body, I know that RS uses 9J according to PET. So that's good news in being able to source other types upto 10J.

Thanks for the photo Lee, it looks great.

Also Kevin, great looking car, is that a turbo body? and those wheels look like Cup 2's with polished rims??

So what tyre pressures do you guys use on those 18's?

They're not Cup 2's. Look like Rufs to me.

 

[911kev]

ORIGINAL: Dekker

Also Kevin, great looking car, is that a turbo body? and those wheels look like Cup 2's with polished rims??

Narrow bodied Carrera 2 with 18" Ruf Speedline wheels. They were silver but had the centres powder coated black and the rim polished.

 

[Dekker]

Yes, very nice looking car Chris, those wheels are similar to ones I want on mine.

So Kev and Chris what tyre pressures do you use on those 18's?

 

[deutschland dobson]

Cheers, photos dont do it justice though. Wish I could take better ones!

Tyre pressures I use are 36 front and 44 rear.

Chris