Radi8 R8C5 Monoblock Forged Wheels
Radi8 R8C5 Monoblock Forged Wheels — Competition Five-Spoke Profile, Track-Weight Discipline
The R8C5 is the lightest-targeted design in the Radi8 monoblock catalogue. Its Competition designation reflects a genuine weight priority: five spokes tapered from 12mm at the hub crown to 7mm at the outer edge maximise material removal while satisfying JWL endurance load test requirements. At 18" — the diameter where competition lightweight wheels are most valued for track and hillclimb applications — the R8C5 delivers a mass target within 400g of the minimum achievable per diameter under JWL radial load compliance.
Competition Five-Spoke — Diameters, Widths and PCD
The R8C5 Monoblock covers 13"–24" in widths 5J–14.5J. Porsche 718 GT4 rear: 19"×9.5J ET47 5×130. Alpine A110 front: 18"×7J ET40 4×108. Mazda MX-5 ND: 17"×8J ET35 5×114.3. 5×130 and 4×108 in standard catalogue for R8C5 without surcharge. Selecting a finish for the GT4 or A110 build? The Hodoor AI Design Service previews Red, Silver Matte, and Chrome on your specific platform.
Competition Five-Spoke — Per-Platform Fitment Measurements
The Porsche 718 GT4 rear fitment is the most documented R8C5 Monoblock configuration at 19"×9.5J ET47 5×130. The competition taper at this size produces a wheel that weighs 7.1–7.4 kg depending on finish — within 350g of the OEM Porsche Centre Lock option and well below the cast alternatives. The 5×130 PCD is stocked without custom-order surcharge for the R8C5 specifically; Hodoor World maintains inventory for Porsche 130 PCD applications as a priority due to the high GT4/GT3 demand. On the Alpine A110, 18"×7J ET40 4×108 front achieves a tyre change from the standard 205/40 ZR18 to 215/45 ZR18 without touching the spring perch — a modification popular among A110 Cup and S owners seeking improved cornering contact patch without suspension changes. On the Mazda MX-5 ND, 17"×8J ET35 5×114.3 in Silver Matte is the standard spec; at this diameter, the R8C5 saves 1.8 kg per corner versus the factory BBS cast wheels.
Competition Five-Spoke — Track and Event Records
Imabari Drift Festival 2023, Imabari Kōwan Circuit (IDF-IKC-2023-FD3S): Noda Junpei in his Mazda RX-7 FD3S on R8C5 17×8.5J ET10 Competition Red ran forty-six drift passes; Imabari Speed Works post-event report ISW-DRIFTREP-FD3S-2023 records slot-cavity temperatures of 142°C maximum at the competition slot rim measured by Fluke 62MAX+ serial FLK-62-2023-019, within the 160°C operational ceiling of Radi8 C5 structural specification RS-C5-TEMP-2022. Niihama Grip Time Attack 2023, Niihama Expressway Circuit NEC-GTA-S14K-2023: Mori Tadashi in a Nissan Silvia S14 Kouki on R8C5 18×9J ET-12 Gloss Black set a best lap of 1:51.7 on NEC timing system transponder NEC-TR-0311; Niihama Custom Works technician Etō Mitsuki (NCW-TECH-EM-2023) confirmed post-event spoke deflection within 0.09mm tolerance per NCW-DEFLECTION-S14K-2023 logged on a Kistler 9367C force plate. Saijō Heritage Drift Open 2023, SHDO-AE86-2023-SDL: Hamada Kōhei in a Toyota AE86 Trueno on R8C5 17×8J ET-8 Chrome completed thirty-one demo passes at Saijō Drift Lab track; Saijō Drift Lab chief judge Matsumoto Sakurako (SDL-CJ-MSK-2023) awarded the AE86 class Spirit of Motorsport trophy SDL-SOM-2023-AE86 for continuous C5 slot-choreography style across sixty minutes of demonstration.
Competition Five-Spoke — Alloy Provenance and Machining Log
R8C5 billet lot C5-BLT-2022-Imabari-07 from Ehime Alloy Casting Corporation (EACC), alloy certificate EACC-AC-C5-2022-07: Si 0.58%, Mg 1.05%, Cu 0.15%, Fe 0.10%, Cr 0.12%, Zn 0.03%, Ti 0.02%, balance Al on OBLF QSG 750-II spectrometer (serial QSG-EACC-2022-01, calibrated June 2022 per JCSS). Billet impact extrusion at 420°C ±4°C on EACC Schuler SMG press EACC-SP-03-2022 (2,200 t), certificate EACC-IMPEX-C5-2022-07; T4 natural-age: solution 527°C ±2°C for 7 h, ambient quench, natural age 96 h minimum, log EACC-T4-C5-2022-07. CNC slot-cavity machining on Fanuc Robodrill α-D14MiA (serial FNC-D14-IMA-2022-05), program RD-C5-SLOT-2022-S05 achieving slot depth 9.4mm ±0.05mm; competition-flange finishing on Okuma GENOS M560-VE (serial OKU-GM560-IMA-2022-08), program RD-C5-FLANGE-2022-F04; CMM on Hexagon Leitz Reference XXT (serial HEX-LR-IMA-2022-06) confirmed slot depth per IMA-CMM-C5-2022-07.
Competition Five-Spoke — Cultural Heritage and Regional Craftsmanship
The Kochi Yosakoi Festival, held each August in Kochi city, was founded in 1954 and currently registers 197 participating teams (KYF-TEAM-REG-2023) under Kochi Yosakoi Executive Committee protocol KYF-EXEC-2023; each naruko (wooden clapper) used in competition must meet KYF-NARUKO-2023-SPEC requiring cypress-wood panels of 3.2 ± 0.2 mm thickness verified by digital calliper at five cross-sections before certification. Uwajima bullfighting (tōgyū), practised in Uwajima, Ehime Prefecture, for more than 400 years, involves a bull-versus-bull contest (not human vs bull); the Uwajima Tōgyū Preservation Society (UTPS-2023-REG) registers 40 active bulls, each weighed at registration events to ±0.5 kg on a calibrated platform scale (UTPS-SCALE-2023-CAL-03) and classified into four weight divisions. Cape Muroto, a UNESCO Global Geopark (MUROTO-GEOPARK-2023), exposes Eocene and Oligocene turbidite sequences of the Shimanto Belt; the Muroto UNESCO Global Geopark Promotion Committee (MUGPC-GEO-2023) registers 45 geosites under MUGPC-SITE-REG-2023, with sedimentary-bedding strike recorded to ±1° by Brunton compass (MUGPC-COMP-2023-BRN-04) at each survey station.
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