Not a winter driving primer. The chain decision: what the law asks of a 4x4, what your owner's manual allows, and what to test before the first storm.
Seven thousand pounds. That is the number on the door-jamb sticker, and the one that matters at the Highway 50 checkpoint below Echo Summit. The sign a mile back said R1. The driver of the lifted half-ton figured four-wheel drive made it a formality. Now he is kneeling in slush with chains bought last night for "a truck like mine."
The chain, a ladder of steel links that drapes over the tread and hooks behind the tire, comes up short because his 35-inch mud-terrain is taller and blockier than its sidewall size suggests. When one side finally latches, the inside run sits a finger's width from the upper control arm. Twenty feet later he hears ticking.
The part he has not found yet is in the glovebox. His owner's manual lists the tire sizes allowed to wear chains, and his 35s are not on it. Had he bought a 2025 Raptor on factory 35s, Ford's manual would be blunter: "We do not approve the use of snow chains on your vehicle's tires."
So snow chains for 4x4 trucks have to clear three bars: the law, the tire, and what the truck maker allows.
Two terms. A chain control is a posted rule on a mountain highway saying who must mount chains right now. A traction device is the legal umbrella for chains, cable chains, and approved alternatives like textile snow socks.
Why this week: on October 10, the National Weather Service in Reno forecast Sierra snow levels falling from 8,500 to 9,500 feet on Sunday, October 11, to about 6,000 to 7,000 feet by Monday morning, with a 60 to 80 percent chance of 4 inches or more on the highest Sierra peaks by Tuesday morning and a 10 to 25 percent chance of about an inch at lake level around Tahoe. Colorado's I-70 traction season opened September 1, under a statute rewritten in August.
Do 4x4 Trucks Need Snow Chains? What the Rules Actually Say
Caltrans spells out California's three levels. At R1, chains are required on all vehicles except passenger vehicles and light-duty trucks under 6,000 pounds gross weight with snow tires on at least two drive wheels, and those vehicles must still carry chains. Check the GVWR on your door jamb: if it is over 6,000 pounds, that snow-tire exemption as Caltrans writes it does not cover you. Caltrans's status chart words R1 differently and exempts 4WD and AWD; at the checkpoint, Caltrans says the signs and officers win. Anything towing chains one drive axle, and trailers with brakes chain at least one axle.
At R2, everything chains except four-wheel and all-wheel drive vehicles with snow-tread tires on all four wheels, and those must carry traction devices in chain control areas. At R3, there are no exceptions. California reads a snow-tread tire off the sidewall: MS, M/S, M+S, or MUD AND SNOW. Most all-terrains carry it.
Colorado has changed its rules twice in two years (SB25-069 in 2025, HB26-1237 in 2026). Under the Traction Law, Colorado State Patrol (CSP) says a 4WD or AWD vehicle complies with chains or an approved device for two or more drive tires, or with M+S, mountain-snowflake, or all-weather tires with at least 3/16 inch (6/32) of tread. Under the Chain Law, every passenger vehicle, 4WD included, needs chains or an approved device on two or more drive tires. CDOT can call either law on any state highway; on I-70 from Dotsero to Morrison, CSP says vehicles under 16,001 pounds must meet the Traction Law whenever it is active, September 1 through May 31.
SB25-069, in effect since August 6, 2025, tied the statute's tire-only option to 4WD and AWD vehicles on marked tires. HB26-1237, in effect since August 12, 2026, strikes that drivetrain wording again. For a 4x4 on good M+S tires, nothing changes. What it means for 2WD drivers is Inference for now: CSP still says 2WD has no tire-only option on I-70, and CDOT's page still showed its "Fall 2025" drivetrain wording on October 7.
Fines depend on whose page you read. CDOT lists $100 plus a $33 surcharge, or $500 plus $157 if your truck closes a lane. CSP lists up to $500 plus $79, or $1,000 plus $157 if you are stuck and blocking the road. Either way, it costs more than the chains.
The Honest Truth: Your Owner's Manual May Already Say No
Even Caltrans tells you to check your vehicle manufacturer's chain specifications. The three 2025 manuals we pulled go beyond a chain class. Ford's two list the exact tire sizes allowed to wear chains, and a size not on the list is a no. Toyota's bars one size outright.
| Truck (2025 owner's manual) | Which axle | Tire sizes approved for chains | Chain limit |
|---|---|---|---|
| Ford F-150 (pp. 554 to 555) | Rear only, in pairs, no self-tensioning chains | 245/70R17, 265/70R17, LT265/70R17, 265/60R18, LT265/70R18 | 15 mm or less (SAE Class S) |
| Ford F-150 Raptor (same manual, p. 557) | None | Neither LT315/70R17 nor 37x12.5R17LT: "We do not approve the use of snow chains on your vehicle's tires." | Not approved |
| Ford Bronco (pp. 440 to 441) | Rear only, in pairs, no self-tensioning chains | 255/70R16, 255/75R17 | 15 mm or less |
| Toyota Tacoma (pp. 438 to 440) | Rear only | None on 265/70R18: "the space between the tire and body is too narrow" | 5 mm side chain, 6.3 mm cross chain |
Ford's 2025 F-150 manual says outright that it does not approve snow chains on the 35- and 37-inch tires its own Raptor wears from the factory. The 2025 Bronco manual names two sizes, neither of them the LT315/70R17 the same book covers. Toyota's 2025 Tacoma manual rules out chains on 265/70R18 tires, the size Goodyear's fitment pages list for the TRD Pro and Trailhunter. If your door jamb or sidewall says 265/70R18, Toyota's answer is snow tires.
Peerless keeps it short: if your manual says do not use chains, do not use tire chains. So once you swap to 35s, the manual has not gone quiet; your new size simply is not on the list. We have not pulled the Tundra, 4Runner, Wrangler, Silverado, or Ram manuals yet, so check yours before you spend a dollar.
The Second Catch: The Chain That Fits Your Tire May Not Fit Your Truck
Even a listed size has a clearance standard. SAE Class S is the Society of Automotive Engineers' minimum space around the drive tires for a traction device. Per Peerless: 1.46 inches from the tread face to the nearest obstruction, 0.59 inch from the inside sidewall. That is less room over the tread than a golf ball is wide, and barely half an inch to your control arm. SAE Class U is the roomier class for regular chains in unrestricted wheel wells.
TireChain.com, a chain retailer, warns that Load Range E, KO2-style, and mud-terrain tires often run larger than a highway tire with the same printed size, and recommends ladder-style link chains for many of them. Peerless's own Quik Grip 2200 LT ladder chain carries a plain note: it does not meet Class S.
So the tire pushes you toward a bulkier chain, and the truck may only have room for a skinny one. Lifted trucks often already run close at full lock or full stuff. Our wheel offset and backspacing guide shows where chains will hit.
Snow Chains for 4x4 Trucks by Type: What Each One Is For
| Traction device type | Typical clearance need | Best job | Watch out for |
|---|---|---|---|
| Class S-rated cable or Z-pattern | Meets Class S when labeled | Stock trucks, tight wheel wells, highway chain control | Not the specialists' pick for aggressive LT tires |
| Twist link ladder | Moderate, often not Class S | General snow on built trucks with room | Rubbing on control arms and liners; needs tensioners |
| Square link ladder | Moderate to high | Durability, frequent winter trips | Heavier and bulkier; confirm clearance |
| V-bar or studded link | Moderate to high | Ice and hardpack climbs | Can damage pavement; pull them on bare road |
| Textile snow sock | SuperSox: 1.20 in tread face, 0.25 in sidewall (Peerless), needs less room than Class S | Highway chain laws on a low-clearance rig | Road tool; check your state accepts it |
| Emergency strap-on | Check brake and wheel clearance | Unsticking in a driveway or lot | Under 5 mph; may not satisfy highway chain rules |
Snow socks are fabric covers that pull over the tread, and Colorado's approved device list includes the AutoSock, ISSE, and EasySox socks, plus Laclede's Alpha Trax.
The Math: Speed, Time, and What a Set Costs
Ford, Toyota, and Peerless all cap chains at 30 mph, and Caltrans posts 25 or 30 inside chain controls. Faster, says TireChain.com, and centrifugal force lifts the chain off the tread: slapping, wear, breakage.
Run it on a pass. A 40-mile chain control stretch at 25 mph is 96 minutes, against 48 at a dry-road 50. That is 48 extra minutes of driving, plus your time on the shoulder putting chains on and off. Caltrans gives you about a mile from the sign to the checkpoint. Use it for the job you already practiced twice in the driveway.
Now the bill. TireChain.com's aggressive-tread chains for 33x12.50R17 ran from $210.99 to $884.53 as of Oct 7, 2026.
Then there is the KO2 tax. TireChain.com's standard 285/70R17 page started at $181.99 for a 4.5 mm diamond chain, with a Class S cable at $186.99, while its aggressive-tread page for the same printed size started at $338.54 for 5.5 mm alloy square with cams, all as of Oct 7, 2026. That is $156.55 more to get in the door, because cable and diamond styles drop off the menu once the tread gets aggressive. Even the identical 5.5 mm alloy square chain was $294.37 on the standard page, $44.17 less, as of Oct 7, 2026. Chains normally come as a pair for one axle; confirm the pack count.
Which axle? Your owner's manual decides, not the chain maker. All three 2025 manuals in the table say rear tires only. Peerless recommends chaining all tires but tells 4WD owners to follow the manual. So a second set only makes sense when your manual approves front chains. Peerless's line still belongs on the dash: four-wheel drive helps you go, not stop. With rear-only chains, scrub speed before the switchback, not in it.
Honest Warts
The first install is always the worst one, so do it in your driveway.
Air back up before you chain up. TireChain.com's install rules say not to deflate tires with chains on, to install them as tight as you can by hand, and to stop after about a quarter mile to retighten. Toyota's Tacoma manual says the same, at 1/4 to 1/2 mile. If you aired down for a snowy forest road, the compressor comes out before the chains go on.
Heavy chains can blow past OEM limits. Several of the beefiest chains on TireChain.com's aggressive-tread pages are 7 mm square link, already thicker than Toyota's 6.3 mm cross-chain limit. Ford's limit is written as 15 mm or less and SAE Class S, so buy against the Class S label, not the wire size.
Pull link chains past the End of Chain Control sign; dry pavement chews up the chain and the road. If chains rub or bang, Ford says stop and tighten them, and remove them if that fails.
Verdict Table: Snow Chains for 4x4 Trucks
| Situation | Smart default | Trap |
|---|---|---|
| Stock 4x4 on factory-size M+S tires | Class S chain in a size your manual lists, on the axle it names | Assuming 4WD means you can leave chains home |
| Lifted truck on 33s or 35s, aggressive LT tires | A winter wheel-and-tire set in a size your manual lists, chained on the axle it names | Chaining a size your manual leaves off the list and hoping the ticking stops |
| Manual bans chains on your tire, or no room | Snowflake-rated tires, a state-accepted sock for carry rules, and a plan B for R3 and Chain Law days | Strap-on emergency chains as a highway plan |
| Towing a camp trailer in California | Chains for one drive axle, plus the trailer axle if it has brakes | Thinking the R2 4WD exemption covers you at R1 |
| Colorado I-70 in a storm | M+S or snowflake tires with 6/32 tread, plus chains or an approved device for Chain Law days | Worn tires that pass the eye test and fail the gauge |
| Frequent winter mountain trips | Chains on the axle your manual approves; a second set only if it approves the front | Chaining the front of a truck whose manual says rear only |
Who Should Buy Which Chains, and Who Can Wait
Buy chains now if you drive California or Colorado mountain highways in winter, if you tow, or if your tires are near 6/32.
Open the owner's manual before a browser tab. If your truck is close to stock and your size is listed, buy the Class S chain it describes, for the axle it names. The paperwork already did the work.
If your tires are a size the manual does not list, the truck maker has already answered. The approved path is a winter wheel-and-tire set in a listed size, and Ford even recommends steel wheels because chains may chip aluminum. Chain an unlisted size anyway and the risk is yours: buy for the exact sidewall and tread, then prove the room at full lock and full stuff before the first storm.
If your winter never leaves the valley floor, you can probably wait; read the winter 4x4 driving guide instead.
FAQ: Snow Chain Questions 4x4 Owners Actually Type
Do 4x4 trucks need snow chains in California?
Yes, 4x4 trucks need to carry snow chains or traction devices in California chain control areas, even when they do not have to mount them. At R2, 4WD vehicles on snow-tread tires skip mounting but must carry devices. At R3, everyone chains up.
Does Colorado's traction law apply to 4WD trucks?
Yes, but a 4WD truck with M+S, mountain-snowflake, or all-weather tires and at least 3/16 inch of tread already complies. Under the Chain Law, it still needs chains or an approved device on two or more drive tires. HB26-1237 did not change that for 4x4s.
Can I put chains on 35-inch tires?
Only if your owner's manual lists that size, and none of the three 2025 manuals we checked approves a 35. The F-150 and Bronco lists stop at factory sizes, and Ford's F-150 manual says it does not approve chains on the Raptor's 35- and 37-inch tires. If you chain an unlisted size anyway, the risk is yours, so test-fit at full lock and full stuff first.
What are SAE Class S tire chains?
SAE Class S chains are built for tight wheel wells, needing about 1.46 inches over the tread and 0.59 inch at the inside sidewall per Peerless. Ford's 2025 F-150 manual calls for Class S chains of 15 mm or less.
How fast can you drive with snow chains on a 4x4?
No faster than 30 mph. Ford, Toyota, and Peerless all set that limit, and California chain controls post 25 or 30.
Do I chain the front or rear tires on a 4WD truck?
Chain whichever axle your 4WD truck's owner's manual specifies, and on the 2025 F-150, Bronco, and Tacoma it is the rear only. Some vehicles call for all four.
Are snow socks legal instead of chains?
In Colorado, yes, when they are on CDOT's approved alternative traction device list, which includes AutoSock and ISSE. Caltrans does not sell or recommend specific brands and points to the Vehicle Code, which requires a traction device permanently marked with its maker and country.
Bottom Line
Snow chains for 4x4 trucks are not optional just because the truck has low range. California wants them aboard in any chain control area, and both states make you mount them at the top level. The harder part for built trucks is the paperwork: your manual may approve chains only on the rear, only on factory-size tires, or not at all. Read the manual, buy for a size it lists, test-fit in the driveway, stay under 30 mph, and take them off when the road goes black again.
Before you buy, run your real tire size through the 4x4 calculators.
Sources
Primary:
- Caltrans chain controls and requirement levels and Caltrans chain control status chart
- Colorado General Assembly, HB26-1237 and SB25-069
- Colorado State Patrol chain law information
- CDOT Passenger Vehicle Traction and Chain Laws
- Ford 2025 F-150 Owner's Manual (snow chains, pp. 554 to 555, and Raptor tires, p. 557, of edition 202407)
- Ford 2025 Bronco Owner's Manual, dealer-hosted copy (snow chains, pp. 440 to 441 of edition 202408)
- Toyota 2025 Tacoma Owner's Manual (winter driving and tire chains, pp. 438 to 440)
- National Weather Service Reno Area Forecast Discussion, issued 2:47 PM PDT October 10, 2026
- Peerless limited clearance and SAE Class S and Peerless traction FAQ (chain manufacturer)
Retailer and fitment (secondary):