IHRA · Hull and handling
IHRA answers this part for 18 of its classes. 3 of those answers permit the part outright and 0 permit it with stated conditions, leaving 15 that do not. 2 of the ones that do not are classes we read as open rather than as refusing it. 5 are inferred from how the class is written rather than quoted from a rule naming this part.
This page is IHRA only, and the bodies do not agree. The same part under IJSBA and UIM. Which one applies to you is decided by whoever sanctions the race you enter.
18 classes, grouped where the same rule gives the same answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules.
OEM part required 4 classes
The original seat base must stay in use. The cover may be replaced, but seat height may change by no more than 12.7 mm either way and the cover may add no more than 12.7 mm.
OEM part required 1 class
Seat base and internal structure must stay OEM stock, with no airflow through the seat or base, and the seat must stay attached throughout the race. Height may rise by no more than 50 mm. The 2021 RXP-X keeps its two-piece seat on the original mounts, within 12.7 mm either way, and the 2017 RXT-X races with its removable rear seat installed. · W.7.5, W.7.5.1, W.7.5.3, W.7.5.4
OEM part required 1 class
Must remain OEM. Modifications allowed. · DD.11
OEM part required 1 class
Modifications permitted but no open holes. If originally two seats, both must be installed. · DD.1
OEM part required 1 class
Modifications permitted, no open holes. Both OEM seats if originally equipped. · DD.2
OEM part required 1 class
OEM seat base; modifications permitted; only one seat required. · DD.3
OEM part required 1 class
Must remain OEM. Modifications permitted. · DD.4
Not permitted, not listed in the rules 2 classes
On a closed list an unlisted modification is not permitted. · A.2.2, J.1
Not permitted, not listed in the rules 1 class
No clause lets in an aftermarket seat or seat base, so on the closed list it is not permitted. The OEM seat may take aftermarket covers and padding, and its height may be modified. · V.9.3, A.2.2, J.1
Legal 2 classes
The seat may be aftermarket or modified, subject to aftermarket seat guidelines that the rulebook cites but never prints.
Legal 1 class
Aftermarket seats are permitted, without the OEM base, open-hole or seat-count rules of the other drag classes. · DD.5
No rule, this is an open class 2 classes
The class states only what it bans and calls itself run what you brung, against a section DD preamble that says anything unlisted is illegal.
Aftermarket seat: if the rule your class applies reads differently to you, or the rulebook has changed since this was read, ask. We answer with the section we read it from, or that we have not read it. Ask a rules question.
Every IHRA class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.
Hull and handling · two and four stroke · legal in 3 of 18 answered