Gravel Carbon Wheelsets Rim Depth: 35 mm vs 45 mm

Last Updated on February 9, 2026 by Vinson Lozano

Gravel has gone from fringe to mainstream, and with it the equipment race has shifted from “survive any terrain” to “survive any terrain, fast.” Among the biggest performance upgrades you can make are your wheels—especially when you step into gravel-specific carbon wheelsets designed around wider tires, tubeless setups, and the unique aerodynamics and impacts of unpaved riding.

This deep-dive compares two popular rim-depth classes for gravel carbon wheels: 35 mm and 45 mm. We’ll explore how depth affects aerodynamics, weight, crosswind stability, impact resistance, comfort, and handling. You’ll find data-backed guidance, scenario-based recommendations, and specific brand suggestions from Zipp, DT Swiss, Lun Grapid, Exxar Gravel Wheelset, and more. The goal is to help you choose the right wheelset for your terrain, tires, speed, and riding style—not just “what’s fastest in a wind tunnel,” but what’s fastest and safest when the dirt gets real.

What Makes a Gravel-Specific Carbon Wheelset Different?

Gravel-specific carbon wheels focus on the interface between a wide, supple tire and a rim shaped to manage airflow and impacts differently than pure road gear. Key design traits include:

• Wider internal rim widths (typically 23–26 mm) to support 35–50 mm tires without lightbulb shaping.
• Tubeless-first or tubeless-only designs, often hookless, optimized for lower pressures and larger casings.
• Reinforced bead walls and impact-resistant layups to absorb rock strikes.
• Aero profiles tuned for larger tires and higher yaw angles at gravel speeds.
• Higher spoke counts and robust hubs for lateral stiffness and durability on rough surfaces.

While some all-road wheels overlap with gravel use, gravel-specific rims improve handling, pinch-flat resistance, and aerodynamics with wide tires. Depth choice—35 mm vs 45 mm—affects how these features translate.

Rim Depth: What It Does And Why It Matters

Rim depth drives three major factors:

1. Aerodynamics
   
   • Deeper rims generally reduce aerodynamic drag, especially at lower yaw angles. On gravel, with speeds in the 20–30 km/h range and mixed winds, yaw angles are often higher than on road, and deeper rims can still help if they’re shaped for wide tires.
   • Realistic wind-tunnel and on-road data with gravel tires commonly show savings in the range of 3–8 watts at 30–40 km/h when moving from a shallow box section to an aero-optimized mid-depth rim. The exact savings depend on tire width, tread, rim external width, yaw distribution, and rider position.
2. Crosswind Stability
   
   • Deeper rims produce more side force and steering torque in gusts. On rough surfaces where stability and precise line control matter, too much side force can be tiring or risky.
   • A well-designed 45 mm gravel rim can be stable, but generally a 35 mm rim will be calmer in variable wind.
3. Weight and Compliance
   
   • Deeper rims often weigh more (typically 100–200 g for the set compared to shallower equivalents) and can feel stiffer vertically and laterally. Those traits can be good for sprinting and precise steering, but they may transmit more chatter on corrugated gravel unless offset by tire pressure and casing choice.

Aerodynamics With Wide Tires: The 105% Rule And Gravel Reality

The common aerodynamic “105% rule” says a rim’s external width should be at least 105% of the inflated tire width to maintain stable attached airflow. On gravel, where tires range from 38 to 50 mm wide, that would require rim externals of roughly 40–53 mm. Few wheels actually go this wide; instead, gravel rims aim to minimize separation losses with broader, blunted shapes and specific nose-to-tail curvature tuned to moderate yaw.

• At 38–42 mm tires, rims with external widths in the low 30s to low 40s and depths in the 35–45 mm range can reclaim a meaningful portion of aero benefit without the extreme widths of a wind-cheating TT bike.
• Because knobby tread raises effective roughness and can cause earlier flow separation, smoother-center tread patterns (file tread or semi-slick) yield better aero outcomes—sometimes worth 1–3 watts compared to a fully knobbed design at the same speed.

Bottom line: Gravel-specific 35–45 mm rims are aero tools when paired with appropriately wide, reasonably smooth tires. You won’t meet road-race levels of CdA, but you can capture practical gains.

Weight, Rotational Inertia, And Acceleration

The mass difference between a 35 mm and a 45 mm gravel carbon wheelset typically lands around 100–200 grams for the set. Two points matter:

• Climbing steady-state:
  • Power to overcome gravity scales with mass, but an extra 150 g in a 75 kg system adds roughly 0.3 watts on a 6% climb at ~12 km/h—not much.
• Acceleration:
  • Rotational energy matters more when repeatedly accelerating, but 150 g near the rim might add on the order of tens of joules to get up to speed. Over a long gravel ride with repeated accelerations, that adds up, but whether it’s decisive depends on your tactics and terrain.

In practice, the difference in mass between these two depth classes is less critical than aerodynamics on fast, open sections and stability on rough, gusty sections.

Handling And Comfort On Gravel

• Compliance: A shallower 35 mm rim can feel slightly more forgiving. Combined with wider tires at lower pressures, it helps reduce chatter and rider fatigue.
• Precision: A stiffer 45 mm rim, often with slightly higher lateral stiffness, can track more cleanly through fast corners and ruts—if crosswinds aren’t sabotaging your line.
• Tire pressure: Hookless tubeless setups with 23–26 mm internal widths let you run safe, low pressures that transform ride feel. For a 75 kg rider on 40–45 mm tires, typical gravel pressures land between 28–40 psi (front lower than rear). Lower pressures amplify comfort and traction, partially offsetting stiffer rims.

Impact Resistance And Durability

Gravel-specific carbon rims feature thicker bead walls and customized fiber layups focused on impact dispersion. Depth can influence durability in nuanced ways:

• Deeper rims can be structurally more robust, but impact distribution and bead wall protection matter more than depth alone.
• Hookless rims reduce stress concentrations and often resist pinch damage better, but they require compatible tires and appropriate pressures.
• Spoke count: 24–28 spokes is common; more spokes distribute load better on rough terrain.

Tip: If you ride very rocky, high-speed descents, prioritize rim construction quality (bead wall thickness, resin toughness, and impact testing) over chasing a few watts from depth alone.

Safety And Standards: Hookless, Tubeless, And Pressure

Many gravel carbon rims today are hookless and tubeless-only. Key safety notes:

• Tire compatibility: Use tires explicitly rated for hookless rims by the manufacturer. Not all tubeless tires are hookless-approved.
• Max pressure: Hookless rims generally impose a maximum pressure around 72.5 psi (5 bar), but that’s far above gravel pressures. Never exceed the rim’s stated limit.
• Insert use: Tire inserts can protect rims against hard hits and permit slightly lower pressures for better grip and comfort, with a small weight penalty.

35 mm vs 45 mm: The Tradeoffs In Detail

Aerodynamics

• 35 mm
  • Pros: Lower side-force in crosswinds; more predictable handling at high yaw and on rough, gusty days.
  • Cons: Slightly less drag reduction compared to deeper profiles at speed on open roads/sections.
• 45 mm
  • Pros: Better aero performance on open, fast gravel with semi-slick tires; can save a few watts at 30–40 km/h, improving overall speed.
  • Cons: More steering torque in gusts; may feel “busy” in variable winds with high-yaw distributions.

Weight And Acceleration

• 35 mm
  • Pros: Potentially 100–200 g lighter; snappier feel in punchy terrain.
  • Cons: On long, flat fast segments, aero could matter more than small mass savings.
• 45 mm
  • Pros: Slight weight penalty is often offset by aero gains in races with long exposed sections.
  • Cons: Can feel marginally slower to spin up in very twisty, stop-start singletrack.

Comfort And Control

• 35 mm
  • Pros: Often marginally more compliant; calmer steering; confidence on technical courses.
  • Cons: Loses time where the terrain is smooth and speeds are high.
• 45 mm
  • Pros: Precise tracking at speed; stability when the rim is well designed for wide tires.
  • Cons: Potentially harsher feel on washboard if tire pressures aren’t tuned.

Durability

• Both can be extremely durable; construction quality matters more than depth alone. Look for reinforced bead walls, proven layups, and strong spoke interfaces.

Data-Based Scenarios: Which Depth Wins Where?

Below are generalized scenarios combining empirical wind-tunnel findings and field experience. Note that exact wattage and speed gains vary with setup, rider position, and environmental conditions, but the directional guidance holds.

1. Rolling Farm Roads, 35–45 km/h, Semi-Slick 40–45 mm Tires
   
   • 45 mm rims often yield 3–8 watts savings at the top end of this speed range compared with 35 mm, assuming aero-optimized external profiles. Over a 3-hour event, that can translate to minutes saved.
   • Crosswinds matter; if gusts are moderate and consistent, 45 mm is manageable.
2. Technical Forest Service Roads, 20–30 km/h, Knobby 42–50 mm Tires
   
   • 35 mm rims reduce steering torque and often feel safer picking lines through rock gardens and ruts.
   • At these speeds, aero benefit shrinks. Comfort and control become paramount.
3. Mixed Course (Open Prairie + Rocky Doubletrack)
   
   • Choose based on your strengths:
     • If you’re a high-power diesel who thrives on open speed sections, 45 mm likely pays back.
     • If you’re more technical, prioritize stability and comfort with 35 mm, especially if you fight crosswinds or run bigger, knobbier tires.
4. Ultra-Distance Gravel (Unpredictable Weather, Fatigue Management)
   
   • Consider 35 mm to minimize handling stress in crosswinds and reduce fatigue from constant micro-corrections.
   • If the route is notably fast and exposed, a well-behaved 45 mm wheel is viable with careful tire selection and pressure tuning.

Brand Recommendations And How Their Lines Fit The Depth Debate

Below are gravel-focused recommendations and how they align with 35 mm vs 45 mm needs. Always verify current specifications and tire compatibility with the manufacturers, as models and standards evolve.

Zipp

• Why consider Zipp:
  • Strong tubeless hookless expertise, excellent rim shaping, and a focus on real-world aero. Widely used across gravel and all-road racing.
• Models and use-cases:
  • Zipp 303 S (approx. 45 mm depth, 23 mm internal, hookless): An accessible, fast option broadly used for gravel and all-road. Pairs well with 32–45 mm tires. Good for open, faster courses.
  • Zipp 303 Firecrest (approx. 40 mm depth, 25 mm internal, hookless): Wider internal supports bigger tires more confidently. Suits mixed gravel courses, offering a balance of aero and stability.
  • Notes:
    • Zipp’s gravel-specific 101 XPLR is much shallower (around 27 mm), optimized for compliance and traction rather than aero. For this article’s depth focus, 303 is more relevant.
  • Recommendation:
    • If your events emphasize speed and exposure to wind, the 303 S or 303 Firecrest can be excellent. Firecrest’s 25 mm internal width is particularly friendly to 38–45 mm tires.

DT Swiss

• Why consider DT Swiss:
  • Comprehensive gravel program with proven durability and thoughtful aerodynamics for wide tires. Hubs are reliable and serviceable, with SPLINE systems that balance stiffness and comfort.
• Models and use-cases:
  • DT Swiss GRC 1400 SPLINE 42 (42 mm depth, gravel-specific aero shaping, internal width commonly around mid-20s):
    • Designed explicitly around 35–50 mm tires and mixed yaw conditions. A strong candidate for riders who want aero gains without sacrificing tire volume support.
  • Other DT Swiss gravel lines include alloy options (e.g., GR 1600), but for carbon depth comparisons, GRC is the benchmark.
  • Recommendation:
    • For fast gravel racing where you still want a tire-friendly profile and balanced handling, the GRC 1400 SPLINE 42 is a standout.

Lun Grapid

• Why consider Lun Grapid:
  • Lun-branded gravel wheelsets are commonly discussed among riders seeking competitive performance without premium pricing. Some Lun gravel offerings are positioned around 35 mm and 45 mm depths.
• Models and use-cases:
  • Look for Lun gravel models that specify internal widths in the 24–25 mm range and rim depths around 35 mm (for stability) or 45 mm (for speed).
  • Recommendation:
    • If you want value-forward carbon with depth options tailored to gravel, Lun Grapid is worth investigating. Verify hookless compatibility, max pressure, and recommended tire widths.

Exxar Gravel Wheelset

• Why consider Exxar:
  • Exxar-branded gravel wheels appear in the market with carbon options targeting the same 35–45 mm depth class. As with any brand, confirm tubeless standards, hookless/tubed compatibility, and rim width.
• Models and use-cases:
  • Seek models with internal widths around 24–26 mm, tubeless-first design, and robust impact testing. Match depths to your course profile: 35 mm for control; 45 mm for speed.
  • Recommendation:
    • Exxar Gravel Wheelset offerings are a candidate for riders balancing performance and budget. Ensure the tire compatibility list is up-to-date and match your intended tire sizes and pressures.

HUNT

• Why consider HUNT:
  • HUNT’s gravel lineup has strong fan support for combining intelligent specs (wide internals, tubeless, good spoke counts) with fair pricing and solid global support.
• Models and use-cases:
  • HUNT 35 Carbon Gravel X-Wide (35 mm depth, often ~25 mm internal):
    • A sweet spot option for technical gravel and mixed terrain. The internal width pairs nicely with 38–50 mm tires for stable casing shape.
  • Recommendation:
    • Pick HUNT’s 35 mm class for stability and comfort on rugged courses. If you find HUNT’s 40–45 mm options, consider them for wind-exposed racing.

CADEX

• Why consider CADEX:
  • CADEX (Giant’s premium component brand) focuses on high-end materials, quality control, and light weight. Their AR lines address all-road/gravel needs.
• Models and use-cases:
  • CADEX AR 35 (approx. 35 mm depth, 25 mm internal):
    • A lightweight option designed for wider tires, offering excellent support for 38–45 mm rubber and a refined ride feel.
  • Recommendation:
    • If you want a top-tier 35 mm wheelset that rides smoothly with big volume tires and remains calm in gusts, the AR 35 is compelling.

Additional Options Worth Considering

• Reynolds ATR (carbon gravel line with options around 40 mm depth):
  • Known for durability and practical specs; a balanced aero-comfort profile for mixed courses.
• ENVE (AG series and AR/SES overlap):
  • While some ENVE gravel wheels sit shallower than 35 mm, ENVE’s all-road shapes can serve gravel racers seeking high-quality rims and hubs with careful tire pairing.
• Reserve (gravel-focused options):
  • Reserve’s gravel line emphasizes impact resistance and trustworthy tubeless setups, with multiple internal width options matched to tire size.

Practical Selection Guide

Use the following filters to decide between 35 mm and 45 mm, and then pick among brands/models that match your profile.

• Typical Average Speed:
  
  • Below 28 km/h: Lean toward 35 mm for stability and comfort; aero savings shrink.
  • Above 32 km/h: Consider 45 mm for real aero benefit; control side forces with tire/tread choice.
• Terrain:
  
  • Rocky, rutted, technical: 35 mm often feels better and tiresome wind steering is reduced.
  • Open prairie, graded gravel, long straight sections: 45 mm likely pays back in reduced drag.
• Tire Widths And Treads:
  
  • 38–42 mm semi-slick or mild tread: 45 mm depth rims can show clear gains without harsh handling.
  • 45–50 mm, knobby: 35 mm rims usually ride calmer and maintain better control at lower pressures.
• Rider Sensitivity To Crosswinds:
  
  • If gusts genuinely stress you—or your local terrain funnels wind unpredictably—stick to 35 mm.
  • If you’re comfortable in wind and want speed, 45 mm is fair game.
• Race vs Adventure:
  
  • Short, fast races: 45 mm with semi-slick tires.
  • Long adventure rides: 35 mm for fatigue reduction and easy handling.

Setup Tips To Maximize Your Choice

• Tire Pressure:
  • For a 75 kg rider on 40–45 mm tires: start around 30–36 psi rear and 28–34 psi front, then adjust for terrain and rim specs. Lower pressure boosts comfort and grip, mitigates harsher feel of deeper rims.
• Tire Selection:
  • Semi-slicks for fast, dry courses; knobby center for loose-over-hard; consistent casing quality is crucial on hookless rims.
• Inserts:
  • Use inserts for rocky courses and aggressive descending; they protect rim beads and reduce pinch risks, letting you run slightly lower pressures safely.
• Tubeless Hygiene:
  • Keep sealant fresh, tape neat, and valves true. Rim-tire air sealing is non-negotiable off-road.
• Hubs And Engagement:
  • Rapid engagement (high-tooth ratchets or pawls) helps in technical climbs and slow-speed maneuvers. Consider center-lock vs six-bolt based on your brake rotor preference and local availability.

Specific Recommendations By Use-Case

• Fast, Open Gravel Racing (e.g., long prairie sections, moderate winds)
  
  • Zipp 303 Firecrest or 303 S (45/40 mm range), semi-slick 38–42 mm tires
  • DT Swiss GRC 1400 SPLINE 42
  • Lun Grapid 45 mm option
  • Exxar Gravel Wheelset in the 45 mm class
  • Reynolds ATR ~40 mm
  • Why: Aerodynamic efficiency at realistic speeds adds up; these wheels are engineered for wide tire shapes.
• Technical Gravel And Mixed Singletrack
  
  • HUNT 35 Carbon Gravel X-Wide
  • CADEX AR 35
  • Lun Grapid 35 mm option
  • DT Swiss (if you prefer a slightly deeper but still controlled feel, GRC 42 can work with knobbier tires and lower pressure)
  • Why: Calmer handling, better comfort, reduced fatigue in gusty, technical sections.
• All-Rounder “One Set To Do Most Things”
  
  • Zipp 303 Firecrest (balances width and moderate depth)
  • DT Swiss GRC 1400 SPLINE 42 (aero but tire-friendly)
  • CADEX AR 35 (light, supportive, calm)
  • Choose 35 mm if your courses are more technical; choose ~40–45 mm if your rides are predominantly fast and open.

Cost, Serviceability, And Ownership Experience

• Carbon Repair/Replacement:
  • Check crash replacement policies; some brands offer generous coverage that reduces long-term risk.
• Hubs:
  • DT Swiss hubs are a benchmark for reliability and parts availability; Zipp’s modern hubs are markedly improved; CADEX provides high-end options; HUNT aims for practical service support.
• Spokes:
  • Straight-pull systems ease build consistency; J-bend allows easier sourcing in remote areas. Gravel touring riders often prefer easily sourced parts.
• Brake Interface:
  • Center-lock is common and neat; six-bolt remains versatile, especially where adapters or rotor choices vary.

Evidence Summary And Real-World Expectations

• Aero Gains:
  • With 35–45 mm rims shaped for 38–45 mm tires, expect measurable but modest drag reductions at 30–40 km/h. You’ll rarely see pro-road gains, but a few watts here and there compound across hours.
• Crosswind Handling:
  • 35 mm rims deliver calmer steering in gusts and at higher yaw angles typical of gravel speeds. A well-designed 45 mm rim can be stable, but sensitivity rises, especially with taller tires.
• Weight Differences:
  • 100–200 g isn’t decisive alone. Prioritize the rim-tire interface and course demands over weight when choosing depth.
• Comfort:
  • Tire pressure and casing construction dominate here. The right tire at the right pressure will let even 45 mm rims feel good off-road, though 35 mm still trends calmer.

Final Recommendations

• If your gravel rides and races feature long, open, fast sections with semi-slick tires and manageable winds, go 45 mm. Expect time savings over hours, cleaner tracking at high speed, and robust construction that handles typical gravel impacts.
  
  • Strong choices: Zipp 303 S / 303 Firecrest, DT Swiss GRC 1400 SPLINE 42, Lun Grapid 45 mm, Exxar Gravel Wheelset (45 mm class), Reynolds ATR ~40 mm.
• If your terrain is technical, gusty, and chattery, or you tend to run bigger, knobbier tires at lower pressures, go 35 mm. You’ll appreciate calmer steering, better comfort, and easy line control.
  
  • Strong choices: HUNT 35 Carbon Gravel X-Wide, CADEX AR 35, Lun Grapid 35 mm. DT Swiss GRC 1400 SPLINE 42 can be viable if you value aero even in mixed terrain, paired with the right tire and pressures.
• If you want a single set for varied riding, consider a mid-depth, wide-internal rim in the 35–42 mm range with proven gravel shaping and hookless compatibility. Pair it with properly rated tires and tune pressures to terrain and load.
  

Always confirm tire-rim compatibility (especially for hookless setups), and match internal width to your tire size. Real speed on gravel comes from combining the right rim depth with intelligent tire selection and pressures, so your bike sails the open flats but stays calm and controlled when the road turns to rocks.

In the end, both 35 mm and 45 mm gravel carbon wheelsets can be “fast”—your course, tires, wind, and comfort define which one is fast for you. Aim for a wheelset whose design aligns with your tires and terrain, then exploit pressure tuning and smart tread choices. That’s how you turn engineering into speed, stability, and a grin when the gravel gets wild.