i have worked in the tire industry for 4 years at americas tire co. and have seen what can go wrong with running spacers and would suggest that if you need to gain some width that you never use a slip on spacer that just gives you less contact with the lugnut to stud. for one you have less threads holding it on and the main cause for accidents is that you have decreased the strength of the stud and made it non hubsentric. if you go with a product like marlin, allpro, or trail-gear what you are doing is keeping it hubsentric, and with the added studs you arn't loosing any strength from the studs. one of the biggest things is when you have the slip on spacer you are taking the contact point of the lugnut that is a cone shape and trying to tighten it to something that is now a flat piece and not recest to match the cone shape for a even distribution of weight causing the lugnut seat to move and loosin causing a wheel to fall off. with the bolt on spacer they retain the same cone shape causing a uniform lugseat so that you have a strong grip and no chance of lossing a wheel as long as you recheck you lugnuts every now and then because the aluminum spacer will compress when you first install them making the lugnuts loosen. the only fall back to bolt on spacers is that you increase stress on the factory studs slightly from increasing the leverage point of the tire. i personally run 1.5" spacers on my truck and feel that there is no problem of running these and have never seen a problem with them as long as after 100miles of installing new spacers you retighten the lugnuts to 100ft lbs. i hope this helps. ps sorry for the wording and spelling i have had a few to drink lol
