Benefits of/ reason for larger rear wheels?SP12 pics please?

[Rob Crutch]

Hi

I'm trying to decide what I want to do with my Chim wheel wise, I thought I'd found the perfect set of wheels, but now they've arrived I'm not happy with the offsets so thinking about going with the (almost ubiquitous?!) SP12/ Pro Race 1.2 set up. I've seen people running both 17" front and rears and 17" front/ 18" rears and not sure which is best?

Can someone tell me why TVR (and many others) use larger rear wheels (but then dropped them when they moved to the Tuscan/ T350 etc?!) and whether or not it would be beneficial for me stay with this set up or not? Also I'd like to run some wider rears if possible, something like an 8.5 or 9" ideally, does anyone have SP12's/ 1.2's in these widths and do they work?

I've done a few searches and found some SP12/ Pro Race 1.2 pics but if anyone has some good photos they'd like to post to help me make up my mind I'd be greatful

Sorry for all the questions, if/ when I order the wheels I want to get them right first time!

Thanks,

Rob

Edit;
Just seen this in another thread, it looks amazing... maybe a little more width on the rear wheels, but really what I'm looking for:
http://www.pistonheads.com/sales/1652359.htm

Edited by Rob Crutch on Tuesday 27th April 11:01

[only me]

Am very pleased with the sp12.

Might want to have a look around this link

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Edited by only me on Tuesday 27th April 16:35

[Rob Crutch]

Thanks Clair, I'd seen the thread but was hoping for some more in depth info ideally

What sizes and offsets are you running?

Rob

[Bobsy]

My chim with Pro Race 1.2s in Anthracite. The fronts are 17" x 7" with 215/40/17s, rears 17" x 8" with 245/40/17s. The offsets are standard for the chim 25 front and 35ish IIRC. In the picture the rears look like they don't fill the arches but in the flesh they look good especially side on. I was going to go for 18" rear but it would have meant a lower tyre profile as the overall diameter has to stay the same. I have to admit they were fitted purely for the look but grip and stability have definitely improved.

[only me]

The fronts are 17" and the rears 18" offsets are the same as original, handling and cornering are greatly improved although the ride is slightly more harsh, however now changed to racing reds as well and feels like a totaly new car for the better !

Tony ( Clair is the wife )

Edited by only me on Tuesday 27th April 19:45

[dumbfunk]

I have the exact same set up as bobsy above and avoided 18" rears because in my experience any additional handing benefit of a fractionally lower profile would fail to negate the substantial disadvantages of more expensive wheels, lots more expensive tyres and a decrease in ride quality on what is already a very stiffly sprung car.

I had the opportunity to drive 2 identical BMWs back-to-back on a number of occasions, both with sports suspension but one on 17s and one on 18s and was in no doubt as to which I preferred as a ride AND handling package.

Either will be a great improvement over the original setup though.


df

[only me]

I accept what df says but just prefer the larger size on the rear like the original 16" 15" set up. The ride is slightly harder but this is far outweighed by the handling and in my opinion looks.

Have never driven one with 17" on back but know that i am happy with my choice of the 18"

[SILICONE KID]

Go for 17`s on all four corners , the rear tyre is a lot cheaper and a slightly softer ride .

215/40/17 245/40/17.

[scotty_d]

I too run 17" all round Oz superleggra's 215/40/17 fronts and 225/45/17 rear would not want a samller profile than this on our roads find them good and dont want any wider than 225 on the rear as the eagle f1's have more than enough grip in the dry and being that bit narrow let the water get out the tyre tread much quicker that the old 245 it had on the car when i first bought it very happy with the set up.

[Dunc HK]

I'm running 215/40-17s on the front and 245/35-18s on the rear. Widths are 7" and 8". Yes, it can feel a little harsh at times, but only on really knackered road surfaces. Only an inch in it, but I do like the look of the bigger rears.

[rev-erend]

Benefits - astetics.

Negative benefits - more unsprung weight, so handling is not so bad. But not to worry you will probably be looking sideways a lot more and travelling slower - as you look at your shinny new wheels in the shop windows

[Full SP]

There are two reasons that SP12 ended up as 17" front and 18" rear - the most obvious is that the factory set-up has 15/16 so when upgrading the proportions of the car look "right" with the same diameter "stagger" front to back. The other reason is that the 8x17 wheel (SP12 or P-C 1.2) is a very different design to the 7x17 (bowed spokes for motorsport applications with big brakes) and looks odd coupled with the 7x17 at the front. We do use the 8x17 in the front (for Cerb etc.) with a 9x17 at the rear because the look then makes sense (bowed spokes at the front with big brakes, deep(-ish) dish at the rear.

[Rob Crutch]

Full SP said:

There are two reasons that SP12 ended up as 17" front and 18" rear - the most obvious is that the factory set-up has 15/16 so when upgrading the proportions of the car look "right" with the same diameter "stagger" front to back. The other reason is that the 8x17 wheel (SP12 or P-C 1.2) is a very different design to the 7x17 (bowed spokes for motorsport applications with big brakes) and looks odd coupled with the 7x17 at the front. We do use the 8x17 in the front (for Cerb etc.) with a 9x17 at the rear because the look then makes sense (bowed spokes at the front with big brakes, deep(-ish) dish at the rear.

Thanks for the info/ background. Will a Chimaera take the 8x17/ 9x17 set up you've used on Cerberas? I'm looking for change my front brakes to the 300mm ST170 setup in the not too distant future, so would have a bit bigger brakes...albeit with still pretty small calipers if that makes any difference?

Thanks,

Rob

[Chimjunkie]

Positives (IMO):

Much stiffer laterally
Wide tyre choice including the new AWESOME Toyo R1-R's
Looks/modernisation
Bigger brake options

Disadvantages (IMO):

Slightly heavier although, with the SP12's, the weight is not much different so i believe
wheel price
Tyre price
Need aftermarket adjustable shocks to get best out of ride/handling

[pauldavies85]

I had 18's rear and 17's front, team dynamics jordan R's.

Not sure about harsh ride, I guess a bit lumpy but is this not a sports car?! Handling better, felt like i had more grip (different tyres I admit). The bible has a really useful table in it for relative sizing.

also looks a lot better!

[SILICONE KID]

I must say your black TVR look stunning.Is it all as it came out the factory except the wheels and stripe .I would prefer it without that stripe ..but a very nice car ..

[Dunc HK]

Thanks! I'm still trying to find out what's standard versus modified. It came out of the Malaysia factory in late 2002. Certainly the wheels, stripe and Nitrons aren't standard. It also has an oil cooler, quad-lamp front-end conversion, sub-woofer in the boot and a mysterious push button next to the rear numberplate.

Dunc

[Full SP]

Rob Crutch said:

Full SP said:

There are two reasons that SP12 ended up as 17" front and 18" rear - the most obvious is that the factory set-up has 15/16 so when upgrading the proportions of the car look "right" with the same diameter "stagger" front to back. The other reason is that the 8x17 wheel (SP12 or P-C 1.2) is a very different design to the 7x17 (bowed spokes for motorsport applications with big brakes) and looks odd coupled with the 7x17 at the front. We do use the 8x17 in the front (for Cerb etc.) with a 9x17 at the rear because the look then makes sense (bowed spokes at the front with big brakes, deep(-ish) dish at the rear.

Thanks for the info/ background. Will a Chimaera take the 8x17/ 9x17 set up you've used on Cerberas? I'm looking for change my front brakes to the 300mm ST170 setup in the not too distant future, so would have a bit bigger brakes...albeit with still pretty small calipers if that makes any difference?

Thanks,

Rob

In theory yes, in practice the only advantage to going to 8x17 (vs 7x17) would be to go to 235/40 tyres (presumably with 255/40 17 on the rear - like on the Cerb) but then these tyres are a lot bigger so clearance becomes an issue. I'm not saying it can't be done, just that the risk would be with you to make them clear the arches etc. If you want to stick with 215/40 17 on the front then there is no logical reason to go to 8" wide on normal road tyres (if you were going to track tyrse it might be different because they they can be VERY wide!).

[Chimjunkie]

Up for sale now though...

[Chimjunkie]

Full SP said:

(if you were going to track tyrse it might be different because they they can be VERY wide!).

Indeed. I had Toyo 888's at 245/35ZR18 and those rubbed on the arches. 235 seems ok though. 888's are MUCH wider than T1-R's