The 245/70R19.5 tire size decodes as a 245 mm section width, a sidewall height that is 70% of that width, and a fitting for a 19.5-inch rim — yielding an overall diameter of about 33.0 to 33.3 inches.
A wrong assumption about the number on your sidewall can leave you with a tire that won’t clear the wheel well or carry your axle weight. Reading 245/70R19.5 takes about a minute and saves you from ordering the wrong rubber for a rig that weighs several tons. The part most owners miss: two tires with the identical size code can still differ in diameter, load, and speed rating.
How To Read 245/70R19.5
- 245 — section width in millimeters, the tire’s widest point sidewall to sidewall. Roughly 9.65 inches.
- 70 — aspect ratio. Sidewall height equals 70% of 245 mm, about 171.5 mm or 6.75 inches.
- R — radial construction, standard for modern tires.
- 19.5 — rim diameter in inches. The only inch measurement in the code, and non-negotiable: a 19.5-inch tire needs a 19.5-inch wheel.
Two sidewalls at roughly 6.75 inches each plus the 19.5-inch rim lands near 33 inches of overall diameter. Published listings commonly show 33.0 to 33.3 inches depending on model.
Why The Same Size Code Isn’t The Same Tire
Two tires stamped 245/70R19.5 can differ in diameter, weight, load capacity, tread depth, and speed rating.
The Michelin XRV 245/70R19.5 lists a diameter of 33.3 inches, width of 9.6 inches, max load of 4,080/3,860 lbs, max pressure of 95 psi, 75 mph speed rating, load range F, 625 revolutions per mile, and approved rim width of 6.5 to 7.5 inches. The Hankook Smart FLEX DH35 245/70R19.5 shows an overall diameter of 33.2 inches, section width of 9.9 inches, tread depth of 17/32, top speed of 81 mph, and a measuring rim of 7.5×19.5, with both 14-ply and 16-ply versions listed.
Same nominal size. The diameter sits 0.1 inch apart, width differs by 0.3 inch, and speed rating jumps from 75 to 81 mph. Revolutions per mile typically run about 611 to 631 depending on model and measurement. None of that shows in the size code.
| Spec | Michelin XRV | Hankook Smart FLEX DH35 |
|---|---|---|
| Overall diameter | 33.3 in | 33.2 in |
| Section width | 9.6 in | 9.9 in |
| Max speed | 75 mph | 81 mph |
| Max load | 4,080/3,860 lbs | Varies by ply |
| Max pressure | 95 psi | Check sidewall |
| Approved rim width | 6.5–7.5 in | 7.5×19.5 (measuring rim) |
| Revs per mile | 625 | Model-dependent |
What To Check Before You Buy
Match wheel width, axle rating, and required inflation pressure to the tire maker’s data.
- Rim width: stay inside the tire’s approved range — examples show 6.5–7.5 inches, a single 7.0-inch measuring rim, or 7.5×19.5.
- Load index and speed symbol: the same size shows ratings such as 129/127L, 133/132L, 135/133K, and 136/134M, with max speeds of 75, 81, or 87 mph. Match sidewall markings to your vehicle’s requirement.
- Dual versus single fitment: load capacity changes between positions.
- Inflation pressure: follow your tire placard and the maker’s load-and-inflation data, not a generic number.
A 33.0 versus 33.3 inch difference can shift wheel-well clearance, speedometer accuracy, and effective gearing. When comparing options, our roundup of tested 245/70R19.5 tires for RVs lines them up side by side. For a fuller walk-through of RV tire load, inflation, and fitment, see the RV Tech Library’s guide to RV tires.
Common Mistakes
- Reading 245 as inches. It’s millimeters — about 9.65 inches.
- Assuming all 245/70R19.5 tires are identical. Sidewall markings prove otherwise.
- Skipping the wheel requirement. A 19.5-inch tire won’t seat on a 19- or 20-inch rim.
- Borrowing passenger-car logic. This is commercial heavy-duty territory with its own load and inflation rules.
FAQs
Is A 245/70R19.5 Tire Really 33 Inches Tall?
Usually. Published listings commonly show 33.0 to 33.3 inches, depending on model and measurement method. That figure comes from two sidewalls of roughly 6.75 inches plus the 19.5-inch rim.
Can I Run This Size On A 19-Inch Wheel?
No. The 19.5 in the code is the rim diameter in inches, and a 19.5-inch tire requires a matching 19.5-inch wheel. It won’t seat on a 19- or 20-inch rim, so the wheel must match first.
Why Do Two Tires In This Size Have Different Load Ratings?
Load rating is set by construction, not the size code. The same nominal 245/70R19.5 shows ratings like 129/127L, 133/132L, 135/133K, and 136/134M, and max speeds of 75, 81, or 87 mph — match sidewall markings to your vehicle’s requirement.
References & Sources
- RV Tech Library. “RV Tires” General guidance on RV tire selection, load and inflation, and fitment.
- Michelin. “XRV 245/70R19.5” Model-specific diameter, width, load, pressure, speed, and rim-width figures.
- Hankook. “Smart FLEX DH35” Model-specific diameter, section width, tread depth, speed, and measuring rim data.
- GadgetsFeed. “Best 245/70R19.5 Tires” Product roundup for shoppers comparing options in this size.