How sensitive are T cars to wheel offset?
Discussion
Given I (still!) haven’t sorted out new tyres I’m awfully tempted to add new 17 inch alloys to replace the 18 inch spiders. As a world class ditherer this means hundreds of hours of research into alloy wheels to go with the hundreds of hours of research into tyres.
Finding wheels would be a lot easier if there was a bit of flex on the offset. I particularly like these wheels which aren’t quite the right spec:
https://www.rimstyle.com/spdrs-brm-sparco-drs.html...
Has anyone tried wheels that deviate slightly from the TVR spec and if so, how did it go?
Finding wheels would be a lot easier if there was a bit of flex on the offset. I particularly like these wheels which aren’t quite the right spec:
https://www.rimstyle.com/spdrs-brm-sparco-drs.html...
Has anyone tried wheels that deviate slightly from the TVR spec and if so, how did it go?
I have also dithered, browsed, investigated and dithered some more before deferring the decision about replacement wheels until HS2 is finished......
So I would be interested to know as well, although I did read a thread on PH which stated that you shouldn't compromise on offset by more than a few mm.
So I would be interested to know as well, although I did read a thread on PH which stated that you shouldn't compromise on offset by more than a few mm.
Not sure what is meant by 'non-existant' or 'decent'. Not been an issue I've experienced. Indeed, not had availability issues getting decent 15-inch rubber for the S or the Wedge.
I'm fairly certain the PCD on the Cerb is the same as on the T cars - and I know it isn't the same as the Wedges
Offsets are different though (if I recall correctly you need 'rear wheels' all round for the 18-inch Spiders on a Cerb.
Don't think you'll have any issues with taking 5mm off the offsets without rubbing issues. Given how wide the build tollerances were at TVR, any greater change may have rubbing issues on your car - but not another. I've gone from 25mm offset to 0 offset on the S3 without rubbing issues and a [most likely a placebo effect ] improvement in handling.
16-inch Spiders are great on the Tam. Noticeable improvement in ride quality and overall handling behaviour. That was having a set or road tyres on the 18s and trackday tyres on the 16s.
I've considered swapping the 18s to 17s. There are some nice Bola wheels and I saw some nice sets at the FoS. The 18-inch Spiders look great but are so soft and buckle too easily.
I'm fairly certain the PCD on the Cerb is the same as on the T cars - and I know it isn't the same as the Wedges
Offsets are different though (if I recall correctly you need 'rear wheels' all round for the 18-inch Spiders on a Cerb.Don't think you'll have any issues with taking 5mm off the offsets without rubbing issues. Given how wide the build tollerances were at TVR, any greater change may have rubbing issues on your car - but not another. I've gone from 25mm offset to 0 offset on the S3 without rubbing issues and a [most likely a placebo effect
] improvement in handling.16-inch Spiders are great on the Tam. Noticeable improvement in ride quality and overall handling behaviour. That was having a set or road tyres on the 18s and trackday tyres on the 16s.
I've considered swapping the 18s to 17s. There are some nice Bola wheels and I saw some nice sets at the FoS. The 18-inch Spiders look great but are so soft and buckle too easily.
Useful info about the Cerb and Spiders. I was going to take a punt on a cheap set of Saturns with tyres just to see how much of a difference 16 inch wheels and tyres made. Won’t bother now. Am making enquiries with wheel manufacturers about getting various wheels made with the correct offset. Why can’t all cars just have the same stud pattern and offset!
SonicHedgeHog said:
Mmm…I guess the lack of replies is an indication of how few people change the alloys on their TVR. Roads are so bad I really want higher profile tyres but think the 16 inch Spiders are a bit too small. Guess I’m going to have to take a punt and cross my fingers.
The TVR section of PH is still regularly visited IME, but you did specifically ask about T cars. 
I have 18 / 17 wheels on my Griff, fitted by the previous owner, and the necessary lower profile makes the ride a little harder, although after market suspension helps. A few mm change in ET (offset) will be OK but large changes may result in them touching the wheel arch edge, or if the other way, require spacers with longer bolts, or risk fouling the inner suspension arms. Smaller wheels with a larger profile will be more comfortable, although as suggested, getting 15 and 16 inch tyres in the speed rating required is more difficult.
I found this site good for comparing differences when doing something similar on my Z4. Went down from 19 to 18” and up two sizes on the aspect ratio.
https://www.wheel-size.com/calc/
https://www.wheel-size.com/calc/
SonicHedgeHog said:
I have just discovered that Bola make a 17 inch variant of their version of the Spider. Rear offset would require a small spacer but it looks like a great way of keeping the original look while improving the ride.
Andy Nicholas at SSC (TVR specialist near me) has been getting Bola wheels for his customers who have 'bent' or otherwise destroyed their Spiders. Yes, you'd need to speak to a supplier about getting different offsets if they are required between front and back, or use a spacer.
sixor8 said:
Andy Nicholas at SSC (TVR specialist near me) has been getting Bola wheels for his customers who have 'bent' or otherwise destroyed their Spiders.
Yes, you'd need to speak to a supplier about getting different offsets if they are required between front and back, or use a spacer.
The rears are the correct spec but the fronts will need a spacer - about 8mm I reckon. Seems like the ideal solution and means I have a set of immaculate Spiders to keep the in garage which will be worth millions when there are no straight ones left.Yes, you'd need to speak to a supplier about getting different offsets if they are required between front and back, or use a spacer.
Yes, I’m still dithering. Who would have thought it would be so difficult to find a set of alloys I like that will actually fit! Anyway, quick question. As it understand it the 18inch Spiders are the following spec:
Front 8.5x18 ET42
Rear 8.5x18 ET33
The wheels l like are 8x17 with whatever offset I like. The question is, does the offset change if my 17s are 0.5inches narrower than the 18s and if so by how much? Is it just half and inch?
Front 8.5x18 ET42
Rear 8.5x18 ET33
The wheels l like are 8x17 with whatever offset I like. The question is, does the offset change if my 17s are 0.5inches narrower than the 18s and if so by how much? Is it just half and inch?
Everyday is an opportunity ..
https://www.oponeo.co.uk/blog/wheel-width-and-et-o...
Should provide you the understanding and answer you seek.
Narrower wheels will reduce the width of tyre you can fit though.
https://www.oponeo.co.uk/blog/wheel-width-and-et-o...
Should provide you the understanding and answer you seek.
Narrower wheels will reduce the width of tyre you can fit though.
I have 3 sets of wheels all fit my t350-
SP12 = FRONT 18X8X36 - tyres 225 - 40 REAR 18X9X36 tyres 255-35
JADE R = FRONT 18X8.5X 35 tyres 225-40 REAR 18X8.5 x 35 tyres 255-35
and set of bog standard standard spiders .
Best fit and ride are the SP12 strong and lighter than spiders , followed by Jade r (bit close on the front ,again lighter than spiders).
Of course having the correct the ride height makes a difference(not slammed like many are ).
SP12 = FRONT 18X8X36 - tyres 225 - 40 REAR 18X9X36 tyres 255-35
JADE R = FRONT 18X8.5X 35 tyres 225-40 REAR 18X8.5 x 35 tyres 255-35
and set of bog standard standard spiders .
Best fit and ride are the SP12 strong and lighter than spiders , followed by Jade r (bit close on the front ,again lighter than spiders).
Of course having the correct the ride height makes a difference(not slammed like many are ).
SonicHedgeHog said:
Very interesting. When you say “best fit” do you mean they look best in the arches? Useful to know the rear offset can be reduced a bit.
So SP12 very good neutral handling good grip ide height set correct (not slammed)
JADE R very slight understeer but you get used to it (shows off your brakes and discs)
Spiders oversteer (a compromise on a t350 as TVR ordered the offsets for the Tuscan)
NB mine has saggy discs so wheel is out a few mil compared to normal + saggy track rod ends for beter geo aledgley
Gassing Station | Tamora, T350 & Sagaris | Top of Page | What's New | My Stuff