New Wheels and Tyres on SD1

Robrover · Post by **Robrover** » Tue Mar 15, 2011 8:13 am

I'm wanting to upsize the wheels on my SD1 from 14 x 6 to 15 x 8 inch wheels (minilite style).

What offset should I go for - I believe standard is ET40 so I thought 30 may work well, remain flush with the bodywork and clear the suspension struts.

I was thinking of fitting either 225/55/15 or 225/50/15 tyres - which would look best and are these likely to cause problems on full lock with hitting the front Vitesse deep chin spoiler or front guard?

Post by **katanaman** » Tue Mar 15, 2011 5:51 pm

what size are the original tyres? With that I can work out your nearest profile with your chosen width.

kiwicar · Post by **kiwicar** » Tue Mar 15, 2011 7:31 pm

Hi
check the back spacing carefully, when Tom Walkinsaw racing were running SD1s in saloon racing they got in all sorts of hassel for moving the some of the rear suspension mounts to fit wider wheels.
Best regards
Mike

Post by **Coops** » Tue Mar 15, 2011 7:50 pm

Marki im interested in this also mate,

did the sd1 have a 3.08:1 axle ratio?
if so what size tyres would of been used?
i have a 3.08:1 axle ratio in my car with 17" rims,

ged · Post by **ged** » Tue Mar 15, 2011 9:43 pm

Coops wrote:Marki im interested in this also mate,

did the sd1 have a 3.08:1 axle ratio?
if so what size tyres would of been used?
i have a 3.08:1 axle ratio in my car with 17" rims,

Hi Coops,

3.08-1 for V8 manual.

Tyres were 195/70 HR14 on a 6J rim or 205/60 VR15 on a 6 1/2 rim

Post by **Coops** » Tue Mar 15, 2011 10:10 pm

ta Ged, now need to work out what tyres i should be running

has 215 40 17s on the rear at present

ged · Post by **ged** » Wed Mar 16, 2011 7:34 am

This may help.

http://www.paspeedo.com/calculator.htm

or for more detail.

http://www.carbibles.com/tyre_bible_pg4.html

It has every thing you ever wanted to know about wheels & tyres and a multitude of other information.

Robrover · Post by **Robrover** » Wed Mar 16, 2011 7:58 am

My current wheels are GBs (Minilite lookalike) 14 x 6 and tyres are Toyos 215x60.

It goes fine but 14 in diam performance tyres are not easy to come by nowadays and I'm limited to Vitesse brakes.

The existing set up was fitted when it was 3.5 with a 3.08 diff; now it's 4.6 with a 3.45 diff.

DaveEFI · Post by **DaveEFI** » Wed Mar 16, 2011 8:54 am

Robrover wrote:My current wheels are GBs (Minilite lookalike) 14 x 6 and tyres are Toyos 215x60.

It goes fine but 14 in diam performance tyres are not easy to come by nowadays and I'm limited to Vitesse brakes.

The existing set up was fitted when it was 3.5 with a 3.08 diff; now it's 4.6 with a 3.45 diff.

The standard Vitesse gets close to tyre rubbing on full lock. The cars I've seen with larger tyres have rolled arches.

You can fit XJS brakes with Vitesse wheels - a very worthwhile upgrade.

kiwicar · Post by **kiwicar** » Wed Mar 16, 2011 3:36 pm

Coops wrote:ta Ged, now need to work out what tyres i should be running
has 215 40 17s on the rear at present

Hi Tony
Assuming you have a .76 overdrive in 5th that gives you about 30mph/ k revs in top and 166 at 5500 revs, or 23/ k revs in 4th and 126 in top at 5500 revs, about right for a 10 to 11 second car crossing the line in 4th gear between 125 and 135 mph .
Have a play here http://www.kabamus.com/garage/gears.html
and here
http://www.tciauto.com/Content/StaticCo ... eSupport=1
Best regards
Mike

Post by **Coops** » Wed Mar 16, 2011 4:43 pm

what ever the 5th gear is for a car going R380 box mate

on the strip i have 205 50 15 drag radials mate,
does that effect the outcome much for the 1/4?

Post by **katanaman** » Wed Mar 16, 2011 7:06 pm

looks like you all have a calculator sorted. T I sent you a calculator years ago that did all the box diff and tyre calculations and gave you graphs. I also have an XL spreadsheet that does the same or if you have a google docs account I can share a version on there with you.

dbv8 · Post by **dbv8** » Wed Mar 23, 2011 3:26 pm

A bit cheeky but....
I have a brand new set of 8 x 17's for sale, see the for sale section.
They are supposed to fit standard arches.
You could fit upto 245's on them