Technically I'm tyred!

[Nick Elliott]

TUS 373 said:
Although I have no personal experience of this, I gather from older threads that TVR have a reputation for being a little slap dash with suspension settings on new cars leaving the factory. I would certainly recommend taking a car to someone who knows what they are doing and getting a 4 wheel alignment. Not expensive and can make a dramatic improvement on some cars.

This is a very true statement the Tuscan was developed with 16 inch wheels and early cars on 18 inch wheels were not very well setup, the 4 wheel alingment makes a big difference as do the 35 v's 40 profile tyres as the tyres now fit the rims properly.As for suspension pick up points I belive they were changed, but later cars also had different springs & dampers as the orignals were too soft.

I now have 18 inch wheels with Toyos , a 4 wheel alingment to the latest settings and Nitron adjustable dampers & springs and the ride & handling are the best I have ever had on any of my TVR's

Nick

[kevinday]

Nick Elliott said:

kevinday said:

Nick Elliott said: I upgraded from 16" to 18" wheels and Toyo tyres,the fronts are 235/40/18 and rears 245/40/18.The speedo reads the same for a given engine RPM so the rolling radius must be about the same.

Nick

Not necessarily so because the speedo drive is taken from the gearbox, therefore it will always be the same for any given engine speed, it just may not be the same roadspeed.

If you post the original tyre sizes I can let you know the differences, if any.

The original fronts were Bridgestone SO2’s front 205/50/16 rear 225/50/16 the diameter of the original rears is 24.8 inches the new rear tyre diameter is 25.7 inches. The difference in revs per mile is 836 (16”) 807 (18”) is 29 revs per mile so the difference in circumference is 77.911 (16”) 80.7389 (18”) = 2.8279 inches so that’s about 82 inches per mile ie not really noticeable on the speedo.

Nick

I have just had my spreadsheet do the sums, results as follows:

Front Original Diameter 611.4mm, New 645.2mm an increase of 33.8mm (5.2%), this would lift the front of the car by 16.9mm.

Rear Original Diameter 631.4mm, New 653.2mm an increase of 21.8mm (3.3%), this would lift the rear of the car by 10.9mm.

In my opinion these changes are too great, particularly at the front, unless you have made suspension set up changes (which you appear to have done).

The speedo will be under-reading by 3.3% which is quite significant in these Gatso days.

I am glad the car appears to handle better now, how is the tyre clearance in the wheel arches?

[Nick Elliott]

I was also a bit surprised about the difference although all the figures are from the Toyo catalogue and they are also show on their web site so I should think they are correct. There is not much room between the wheel and the wheel arch, adjusting the front suspension is quiet an arm aching exercise! On the speedo error I suppose all Tuscans with Toyos must be the same unless any have been re-calibrated.

Nick