What are the pros and cons to each?
Is one type favoured against the other for track or daily driving?
Thanks,
bolt ons come with studs, so no need to press out and put longer studs in. Thats what i like about them. SO if you do get better offset wheels you can just unbolt them and away you go.
Bolt on spacers are better, bolt on spacers always have their own studs, if you use them, your not increasing the length of the studs, hence your not putting more stress on them, hence theyr not gonna snap. Its the same thing as running a lower offset wheel. Even if you were to bolt on 3 bolt on spacers together, it would still be ok, because the amount of load would go onto each seperate stud which isnt long. However if you were to get isanely long studs and like a 30mm spacer, the amount of lateral leverage force on that stud diameter would increase, and it might snap. Also bolt on spacers tend to have a tapered lugnut bolt on hole, so that helps centering, rather than having the spacer slide around on the hub which is dangerous. Make sure you get quality spacers, imagine your wheel coming off at 150km/h.
I just wanted to confirm that you’re referring to something like these:
http://www.upgrademotoring.com/wheels/kics_spacer.htm
http://www.optionimports.com/5065662a.html
I’ve noticed that only 25+mm are bolt-ons while anything less extended studs+slip on. Can anyone confirm this? (or am I not looking hard enough)
bolt-on spacers are not awesome because they are all made in China and one thing you do not want to fuck with is inferior wheel studs.
somethings are just metal, catch can, thanks China, subframe spacer, merci Le Chinois, wheel studs? stick with stock or ARP.
I have owned H&R bolt on spacers, Touge Factory bolt on spacers etc. they both sucked and the issue was the studs.
If you are going to use spacers get proper extended studs from ARP.
I run simple plate spacers, 1/4" on all 4 corners right now, and if i planned on doing it long term i would have genuine hub centric spacers machined. I have ARP extended studs.
everything less is a compromise.
try using cheapo bolt on spacers and reefing your wheels on and off twice a week… see how long they last.
AFAIK there are a variety of race / drift series’ or sanctioning bodies that will not allow you to participate if you are running spacers or certain kinds of spacers… they are not safe unless you are doing it right.
tru would you trust a turbo from china
I’d trust a mail order bride from China 
I have been running 25mm H&R spacers in the front and Project Kics 30mm spacers in the rear for over 2 years and have not had any problems. I also went to over 10 autocross events and 1 lapping day with them. These are the bolt on style.
the easiest thing to do…get rims in the right offset for your car!