SP250 - That Narrow Rear Track

[smithgor]

The overly narrow rear track on my SP250 is something I would like to address as the appearance irritates me somewhat.

The car is on steel wheels which are dark blue/black like the body and I think a lighter colour would be better. Since the MOT found a leaking inner axle seal I'm into removing the hubs anyway so maybe I should bite the bullet and fit wires. I'd probably go for MWS. As for tyres I'll be sticking to 165/15 as the retention of the original steering is a non-negotiable.

My question, to someone who has fitted them, is therefore whether the rear track is altered by the fitment of MWS 5J wire wheels and integral hubs (not the bolt-ons, which I know give an extra 1.25"). I suspect not, since MWS do not mention it for the hubs, but I'm not clear about the inset/outset of the wires.

A trawl of the old and new forums shows opinions somewhat split on the use of bolt-on rear hubs for the rear but, whilst I understand what can happen 'in extremis', I cannot see why (properly fitted and regularly checked) they should not be as safe as bolt on steel wheels for normal road use. I'm therefore tempted to go this route on the rears if its the only way to get the rear track widened to better match the front.

[Ian Slade]

Track depends on the offset, I used 5.5J TR6 wires on one SP and Morgan 4x4 5J wires on the other both of which gave a wider track than the standard steel rims, on most cars increasing the rim width usually increases the track as there is not normally enough clearance to change the off set to be positive, ie the extra width is towards the body.

[David S]

Agreed!
And with more offset you are less likely to have the wheels touch the inner wings on full lock.
I decided spokes were too expensive, too common now and too much work keeping clean!
I fitted 5.5" wide Minilites from the TR Centre when my steel wheels were getting spots of rust. The Minilites are low maintenance and fill the arches nicely; they have a greater offset too, and I use an existing steel wheel as a spare..... If you go for wires you need five.
Send me a p.m. if you want some pictures.
I've been vaguely thinking of getting my [silver] old wheels tidied up so I'd have two sets to use depending on the occasion. Maybe some 185s and some 165s? My colour choice is either cream, silver or dark blue [body colour]. I won't go for yellow or anything outrageously modern. All this choosing slows the process somewhat so it may never happen!

David

[David S]

Gordon,

I sent you some pictures via personal email.
There is, of course, the option to put spacers in behind either steel wheels or any splined adapter flanges on the back if you go for wires. Note that although it is not necessary to fit spacers with alloys the studs are not long enough to do this anyway.

As a footnote, I sometimes wonder if there is a modern 16" or even 17" wheel that fits our studs so that modern low profile tyres of the same rolling diameter could be used? ....... just a thought...

David

[Vortex O'Plinth]

......As a footnote, I sometimes wonder if there is a modern 16" or even 17" wheel that fits our studs so that modern low profile tyres of the same rolling diameter could be used? ....... just a thought...
David

This is aTR6 running 17" x 7.5" Rota RB alloys......

Since TR6 steel wheels are a popular swap for cracked SP ones, the stud hole pattern should fit. I don't know the ET of the wheels and, apart from looking hideous, I suspect they'd be tricky to fit. Demon Tweeks stock Rota wheels so I guess these should be relatively easy to find.

[tjt77]

has anyone done comparisons for actual axle width and interchangeability ? the TR2/3/4 rear axle appears to be close in design and would likely be a viable swap..albeit with 'lower' ratio.. I am aware that some have used the BMC 'C' series rear axles sourced from the big healey ..which would require different wheels if using bolt on steel wheels ( style of wheel is almost identical to SP..except its a 5 stud) but the advantage is its strong and easy to change the diff ratio, although taller ratios that 3.9 are not common.. and I believe the SP used a 3.54 or something close...although a 3.9 would be fine IF you have overdrive or a 5 speed... as for wheels.. the triumph TR's have more offset than some others.. Ive used TR3 wheels on MGA's to widen track.. ( same rim width.. bigger offset) and also TR6 wheels for wider rim to allow for more choice of tyre size ( 195 -205 section tyres fit the TR6 rims well) the standard rims are best suited to 165 section.. seems to be plenty of choice for wire wheels too.. both stronger with more spokes and wider rims are readily available.

[David S]

Thanks for the TR6 picture; I don't like the silver band round the hood but feel the wheels aint too bad... it's the tyres that are too big! Each to his own eh?

More to the point..... Does anyone's front wheels ever touch the inner wings? – mine used to before I put on my Minilite alloys.
So, today I have measured the offset on both sets of wheels.
The steel wheels are 5” across the rims, the depth to the flange from the back edge is 4" so the offset is 1½” [37mm]
Using the same procedure I found the offset on the Minilite alloys to be just ¾” [20mm], [The Minilites are 6½ wide and same 4” to the flange], so that is why they don’t touch the inner wings on full lock. I had always thought it was because the inside of the tyre’s edge was held further out due to the wider rims.

Regardless, my view is that wire wheels look good when they are clean, but if you use the car a lot or don't want to spend more time cleaning it than using it the standard wheels are better. However, they caught my inner wings so I fitted easy clean Minilites.

Job done!

[Ian Slade]

The lock stop is adjustable, any of the standard wheels will hit the inner wing if not adjusted correctly even with 165 tyres on original steels which are only 4J

[David S]

Just found a really good website for comparing tyres and wheel offset combinations to fit any car:

https://www.willtheyfit.com/index.php?w ... offset2=46

I played with it for a while comparing all sorts with the radial 165/80x15 tyres on standard steel 37mm offset wheels and it seems really useful and interesting.

David