Wheel and Rim Compatibility
Short answer: Whether a wide wheel/tire fits depends on backspacing and tire size, and every car differs slightly — so measure rather than guess. Factory 14×7 and 15×7 wheels are ~4″ backspacing; on a wider wheel, keeping 4″ pushes the extra width outboard, while more backspacing (e.g., 4.5–5″) splits it inboard.
- One member measured ~5″ of usable backspacing on his 1968 and fit a 265/50R-15 (8″ wheel) without it sticking out — no rubbing on new stock-replacement 5-leaf springs/KYB shocks (rear sat ~3″ high, hoping to settle).
- A 275/50-15 (~10.8″ wide) would protrude past the wheel opening and need the car raised. Watch tire height too: a 275/50-15 is ~25.8″ tall vs. a 275/60-15 at ~28″.
- Measure method: pull a wheel and measure backspacing; remount and measure inside/outside clearance (allow ~1/2″ for axle side-play plus up/down movement). Likely contact points: the top of the inner wheelhouse, the leaf spring, and the lower shock mount. The result tells you how much wider you can go and what backspacing you need.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
← Frequently Asked Questions
I have a 1968 firebird that I would like to put the widest rim and tire on as possible. Will a 15″ x 10″ wheel with 5.5″ back spacing and a 275/50-15 tire fit in the rear wheel house ? I have hotchkis rear suspension and sway bar with true-trac trac adjustable traction bars and KYC gas shocks ( staggered ). Without the traction bars preloaded, I have approx. 3″ of space between the tire and quarter wheel opening. I currently have 245/60-15 and 15″ x 8″ rims with 4.5″ backspacing . With limited upward suspension travel , and anti-sway bar to control side to side movement it may work. Can u advise one way or the other please ? thank you