im new to the forum, so sorry if this has been asked millions of times before, but i keep being told to upgrade the wheels on my
mk1 s-special i must not replace with aftermarket wheels with the wrong offset, as it will ruin the handling and wear out the suspension much faster, yet i see an awfull lot of mx5s with aftermarket wheels on. i have the std 14 inch wheels on but only want to go up to 16 inch.i understand the weight is very important, but when i look websites for wheels no one seems to list wheels with an offset of et45, im no expert on these matters but have any members any advise on this matter, cheers guys carl
The answer is no. Mazda did fit 45s to Mk1s,including 15" wheels, but then went to 40 for 15" wheels only on the Mk2. Special edition wheels wheels fitted by Mazda UK were very rarely 40 or 45 offset. By the time the Mk2.5 rolled out, Mazda had given up any pretence over the offset issue, with many factory designs not conforming.
Changing the offset makes little difference, unless you go wildly away from what was intended. Of course, a wheel with less offset won’t fit.
Ditto weight; I can’t tell any difference between lightweight factory 15" BBS and factory fitted 15" heavy Panasports. But, again, its all within reason. I could tell when a set of 22lb heavy 17s were fitted.
As SAZ says, MCL stuck all sorts of wheels on UK cars, rarely conforming to the proper offset. Many were cheapish TSW designs. The correct offset should (in theory) give optimal scrub radius and less strain on the suspension than, say, ET 35 wheels. However, sometimes less offset is needed because otherwise a wide tyre would hit the suspension and/or you just want the wheels to look bigger by sticking out a bit more.
I’ve currently got wheels of ET40 plus 30mm of hubcentric spacer - so an effective ET of 10 (mostly for wheel clearance due to my long throw steering rack, but also to provide brake caliper clearance). My car has been run like this for about 5 years of track abuse as well as lots of road miles.
I doubt an average driver could tell the difference, certainly I have had no issues with iffy steering feel or handling problems (although it is entirely possible I’m a cack-handed idiot). My wheel bearings are standard and as far as I can tell are the ones fitted in the factory 150,000km ago.
Al Clark used to run 8 offset, 8" wide Panasports on his 1.6 which was still capable of a sub 9minute lap of the Nurburgring so I don’t think you have much to worry about.
After seeing pictures of the rear brake upgrade you made fit your car… I think the odds of you being as you said, “a cack-handed idiot” are Pretty frigin’ low. [:D]
It might be worth reconsidering going to 16" wheels. The choice of tyres is much lower and the sidewalls are lower, giving a poorer ride. Many people consider 15" to be the best. It could be worth having a browse through this and other forums before you commit.