---
title: "Drill down into a generation: per-vehicle modifications with OEM specs and fitment deltas (package)"
method: GET
path: "/v2/classified/by_package/search/modifications/"
tags: ["Classified methods"]
---

# Drill down into a generation: per-vehicle modifications with OEM specs and fitment deltas (package)

`GET /v2/classified/by_package/search/modifications/`

## Request

- Base URL: `https://api.wheel-size.com` (the document declares no server; this is the origin it was published from)
- URL: `https://api.wheel-size.com/v2/classified/by_package/search/modifications/`
- Auth: API key in query parameter `user_key`
- TypeScript: <https://skmtc.dev/wheel-size/apis/wheel-fitment-api/docs/v2/classified/by_package/search/modifications/get.ts> (a function with typed inputs; its response is checked against the schema)

Given a specific generation from the `by_package/search/` hierarchy, returns individual trims/modifications with their OEM wheel specs and per-vehicle fitment data.

Each result includes the vehicle's OEM rim and tire specs, frontspace/backspace in mm, and deltas showing how much the searched package differs from the OEM fitment. When `cb` (centre bore) is provided, `cb_diff_mm` shows the hub bore difference.

## Query parameters

- `bolt_pattern` string, required
- `rim_diameter` number, double, required
- `rim_width` number, double, required
- `rim_offset` number, double, required
- `cb` number, double
- `fd` number, double
- `fs_poke` integer
- `bs_push` integer
- `rim_bst_from` integer
- `rim_bst_to` integer
- `od_tolerance` number, double
- `ow_tolerance` number, double
- `diameter_range` integer
- `sort` 'name' | 'fitment' | 'load'
- `section_width` integer, required
- `aspect_ratio` integer, required
- `make` string, required
- `model` string, required
- `generation` string, required
- `limit` integer
- `offset` integer

## Response `200`

- VehiclesByPackageGenerationReportOutput
  - `data` VehicleData[], required
    - `slug` string, required: Identifier for the element. Value is a hash based on ID
    - `trim` string, required
    - `body` string, nullable, required
    - `production_start_year` integer, required
    - `production_end_year` integer, required
    - `regions` unknown[], required
      - unknown
    - `oem_rim` string, nullable, required
    - `oem_tire` string, nullable, required
    - `oem_rim_diameter` number, double, required
    - `oem_rim_width` number, double, nullable, required
    - `oem_rim_offset` number, double, nullable, required
    - `oem_frontspace_mm` number, double, required
    - `oem_backspace_mm` number, double, required
    - `fs_delta_mm` number, double, required
    - `bs_delta_mm` number, double, required
    - `cb_diff_mm` number, double, nullable, required
    - `load_kg` number, double, nullable, required
    - `load_index` integer, nullable, required
  - `meta` ClassifiedMeta, required
    - `count` integer, required
    - `offset` integer, required
    - `limit` integer, required

## Changes

- **2026-09-18** `dd21f21710f3`: 2 info
  - `query` request parameter `rim_bst_from` was deprecated
  - `query` request parameter `rim_bst_to` was deprecated
- **2026-09-17** `7fcbbffc6275`: 3 breaking, 1 warning
  - the response property `data/items/oem_rim` became nullable for the status `200`
  - the response property `data/items/oem_rim_offset` became nullable for the status `200`
  - the response property `data/items/oem_rim_width` became nullable for the status `200`
  - deleted the `query` request parameter `ordering`

[Operation history](https://skmtc.dev/wheel-size/apis/wheel-fitment-api/changes/v2/classified/by_package/search/modifications/get.md)

---

[API](https://skmtc.dev/wheel-size/apis/wheel-fitment-api.md) - [All operations](https://skmtc.dev/wheel-size/apis/wheel-fitment-api/llms.txt) - [OpenAPI document](https://skmtc.dev/wheel-size/apis/wheel-fitment-api/revisions/0283a9f8acf0?raw)