Whilst pondering what to do about wheels and tyres, and specifically offset, I measured up the car and found that my track at the front is roughly 145cms, but to fill the arches at the back, I'd need more like 155cms.

Am I right in saying that Sierra front hubs need et40? That's what's on, and it certainly looks about right for the front. However, at the back, even with 25mm spacers in, the wheels are too far in. I don't fancy using bigger spacers.

Current tyres are perished, but I don't want to replace if the wheels are also wrong.

Compound my dilemma, the fact that there are some pro race 1.2 on ebay at a good price, et25 which might sort the look at the back, but they need tyres too!

Aware that I've not really asked anything specific there! Just thinking out loud....

I used to have a document listing all the offsets! A quick search shows ET39-43 was standard on the Sierra - if you hit the search button and plough through all the hits on here there will be a wealth of info as it was a hot topic about 15 years ago. I can’t remember if the conclusion was that you could use a different offset - the Sierra was designed as a FWD car so the offset is more typical for that, rather than RWD, but I remember seeing diagrams about the front geometry!

My sierra based MAC#1 (same as an MK) use ET38, I have pro race 1.2's on and they fill the arch perfectly.

4 x Wheels- 15" Team Dynamics Pro-Race 1.2 7 inches wide,108 mm pcd Ford fitting ET 38 offset

4 x Tyres - 195/50R/15