For the most part, 15mm spacers require the use of extended wheel bolts. Because 15mm wheel spacers shorten the bolt length which directly contacts with the hub assembly. For instance, if the OE wheel bolt length is 30mm and you get a 15mm wheel spacer installed, then you would need longer wheel bolts with 45mm length (stock bolt length + spacer thickness = extended wheel bolt length). Not enough bolt threads cause wheel safety issues. The wheel cannot be fastened properly. You can experience vibration at driving, even worse, the wheel will fall off the vehicle. Considering the interference of wheel lug holes, the bolts can be a little longer. However, if the bolts are too long, they cannot be torqued correctly. When you are in process of installing 15mm wheel spacers, make sure you get the correct extended wheel bolts.
Seat Types of Extended Wheel Bolts
If you plan on running 15mm spacers with stock wheels, you need extended wheel bolts with the same seat type as the stock ones. If you intend to run aftermarket wheels, then both radius and conical seats are possible. Using a wheel bolt with the wrong seat type would make the wheel simply not be fastened to the hub correctly. Thus, it is important to figure out which type is suitable before buying them.
BONOSS extended wheel bolts are designed with floating seats. The floating seats are replaceable which allows for a perfect fit on any wheel. They are mainly available in two options depending on lug bolt size: conical seat and ball seat (R13 or R14). Besides, the separate design eliminates the bolts loosening and abnormal sound caused by the PCD hole coaxially deviation between the vehicle hub and wheels while driving. Since the floating seats are not fixed, they can effectively prevent your beautiful wheels from being scratched by the bolts.
Extended wheel bolts are very important parts to lock the spacers and wheels in place. And people always use high-grade bolts for critical applications. Steel is strong and hard. BONOSS forged SCM440 steel extended wheel bolts have achieved ISO Grade 12.9 standards (tensile strength is up to 1,282 Mpa). The Titanium extended wheel bolts will ensure a safe thread engagement while reducing the unsprung weight. As the weight savings, you will get a better driving experience. Lighten the vehicle weight decreases fuel consumption and improves engine efficiency, to some extent. Furthermore, BONOSS shell-type extended wheel bolts kit consists of standard extended wheel bolts and aluminum shells. The shells are engineered in different colors which maximally beautify your wheel while protecting the bolts from debris and water corrosion. By installing BONOSS shell-type extended wheel bolts, you can even make the vehicle look good, personalized, and different.