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OTR Grassmaster 18X9.50-8 B/4PLY Tire

Lawn&Garden/Golf Cart
Lawn and Garden

Rims Not Included

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7.8 Great

Availability

In Stock

Per Tire:

$32.50

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Category

Lawn&Garden/Golf Cart | Lawn and Garden

T804189508

This listing is for new OTR Grassmaster 18X9.50-8 B/4PLY Tires. Manufacturer part number: T804189508.

The OTR Grassmaster is a high‑performance tire designed for zero‑turn mowers, garden tractors, riding mowers, and utility vehicles. Engineered to provide optimal traction and handling without damaging turf, this tire is ideal for landscaping professionals and homeowners who want to maintain a pristine lawn while ensuring durability and long‑lasting performance.

Its specialized S‑shaped tread pattern provides superior grip, especially during sharp turns and when navigating grassy and uneven surfaces. The tire is built with a durable rubber compound that resists wear and tear, ensuring reliable performance even under heavy use. Its tread design minimizes turf damage, making it a great choice for maintaining delicate lawn surfaces while also offering excellent stability in wet or dry conditions.

Ideal for: Zero‑turn mowers, garden tractors, riding mowers, and utility vehicles used for lawn maintenance and turf care.

Tire Features & Benefits:

S‑shaped tread design provides strong traction while minimizing turf damage
Durable compound supports long tread life, even under heavy use
Designed for optimal handling on grass, turf, and light off‑road conditions
Provides superior stability for smooth, consistent operation
Available in a wide range of sizes to fit various lawn equipment models

For nearly 10 years, Giga Tires has served the online tire community. With over 1 million tires sold, 24K+ 5-star reviews, and thousands of tires at your fingertips at unbeatable prices, see for yourself why customers choose Giga as their online tire shop.

1+ Million Tires

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Over 24K 5-star

Customer Reviews

10+ Years

In Business

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Convenient financing options

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About the Manufacturer:

OTR Wheel Engineering, founded in 1987 in the USA, is a market-leading specialist in off-the-road (OTR) tire, wheel, and complete assembly solutions. Operating with strategically located facilities across North America and Europe, OTR Wheel Engineering is trusted for its innovative engineering and customized products, offering robust durability, reliability, and application-specific performance for heavy equipment in agriculture, construction, mining, and turf care.

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Name

Brand

Size

Price

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Specifications

Specs

Value

Description

Load Range/Ply Rating

B/4PLY

Ply rating, more commonly referred to as load range, represents the strength and durability of the tire. Higher ratings may indicate your tires can handle heavier loads.

Max Single Load(lbs)

935

The maximum load this tire will support. Remember to multiply this number by the number of tires installed on your vehicle to get the maximum carrying capacity. This number is directly related to the Load Index.

Max Single Air Pressure(PSI)

The maximum air pressure this tire will support. This does not represent the amount of air pressure your tires should have at all times. Consult with your owner's manual to determine the best air pressure you should use for your vehicle.

Measured Rim Width

7.0

The recommended wheel width as recommended by the tire manufacturer to get the best wear us performance for this tire.

Section Width

8.78

The measurement from sidewall to sidewall.

Overall Diameter

18.2

The height of the tire when fully inflated.

Manufacturer Part Number

T804189508

Manufacturer part number (sku)

Financing

You can pre-qualify to finance your tires, or you can simply choose Affirm at check-out. Fill out your information and choose the monthly payment that works best for you!

Select 3, 6 or 12 monthly payments, with rates from 10% - 36% APR. 18 months financing available for orders over $1000.00

Checking your eligibility won't affect your credit. You will receive an immediate answer from Affirm.

Affirm has no hidden fees or costs and is completely secure.
Quick and easy, real tire financing, real fast! You can apply in advance and know you can shop for tires when you are ready.

To learn more visit Buy With Affirm or read their convenient Affirm FAQ's. All credit decisions are made by Affirm.

To contact Affirm regarding your account, please call 1-855-423-3729.

No hidden fees

Affirm has no hidden fees or costs and is completely secure

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You choose the payment schedule that works for you

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Pay over time

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No Credit? No problem!

Lease your tires with Katapult!

With a small down payment, and easy payments you can lease your tires. Payments are coordinated with your payday. Read more here about how Katapult works.

No credit required

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Learn more about Katapult lease-to-own tire financing

Size Details

Size	UTQG	Load Range/Ply Rating	Overall Diameter	Section Width	Rim Width Min	Rim Width Max	Rim Width Meas	Tread Depth (in)	Max Single Air Pressure (PSI)	Max Single Load (lbs)	Max Dual Air Pressure (PSI)	Max Dual Load (lbs)	MFG #
11X4.00-5	-	A/2PLY	10.87	4.0	-	-	3.0	-	22	210	-	-	T802114005
15X6.00-6	-	A/2PLY	14.17	5.94	-	-	4.5	-	14	570	-	-	T802156006
15X6.00-6	-	B/4PLY	14.17	5.98	-	-	4.5	-	14	365	-	-	T804156006
16X6.50-8	-	B/4PLY	15.98	6.38	-	-	5.375	-	28	615	-	-	T804166508
16X7.50-8	-	B/4PLY	16.0	7.0	-	-	5.375	-	22	760	-	-	T804167508
18X6.50-8	-	B/4PLY	17.0	6.5	-	-	5.375	-	28	770	-	-	T804186508
18X7.00-8	-	B/4PLY	17.6	6.97	-	-	5.375	-	26	785	-	-	T804187008
18X8.50-8	-	A/2PLY	17.72	8.27	-	-	7.0	-	22	825	-	-	T802188508
18X8.50-8	-	B/4PLY	17.83	8.62	-	-	6.375	-	22	825	-	-	T804188508FP
18X8.50-8	-	B/4PLY	18.33	9.11	-	-	7.0	-	24	825	-	-	T804188508
18X8.50-10	-	B/4PLY	17.7	8.0	-	-	7.0	-	22	780	-	-	T8041885010
18X9.50-8	-	B/4PLY	18.27	9.25	-	-	6.375	-	24	935	-	-	T804189508FP
18X9.50-8	-	B/4PLY	18.2	8.78	-	-	7.0	-	24	935	-	-	T804189508
18X10.50-10	-	B/4PLY	18.5	9.92	-	-	8.5	-	20	990	-	-	T80418105010FP
18X10.50-10	-	B/4PLY	17.95	9.92	-	-	7.0	-	22	990	-	-	T80418105010
20X6.50-10	-	B/4PLY	19.6	6.7	-	-	5.5	-	24	840	-	-	T8042065010
20X8.00-8	-	B/4PLY	19.96	8.23	-	-	6.5	-	22	965	-	-	T804208008
20X8.00-10	-	B/4PLY	19.6	7.7	-	-	6.5	-	22	850	-	-	T8042080010
20X10.00-8	-	A/2PLY	19.17	10.16	-	-	8.0	-	10	600	-	-	T8022010008FP
20X10.00-8	-	B/4PLY	16.69	9.8	-	-	8.0	-	22	1200	-	-	T8042010008
20X10.00-10	-	B/4PLY	19.49	9.17	-	-	7.0	-	22	1170	-	-	T80420100010
20X10.50-8	-	B/4PLY	19.0	10.3	-	-	-	-	22	1250	-	-	T8042010508FP
20X12.00-10	-	B/4PLY	19.9	11.0	-	-	8.5	-	20	1320	-	-	T80420120010
22X9.50-12	-	B/4PLY	21.57	8.78	-	-	7.0	-	22	1170	-	-	T8042295012FP
22X11.00-10	-	A/2PLY	21.1	11.0	-	-	8.5	-	10	1050	-	-	T80222110010
22X11.00-10	-	B/4PLY	21.5	11.1	-	-	-	-	21	1050	-	-	T80422110010
23X9.50-12	-	B/4PLY	22.83	9.41	-	-	7.0	-	20	1225	-	-	T8042395012FP
23X9.50-12	-	B/4PLY	22.95	9.21	-	-	7.0	-	24	1375	-	-	T8042395012
23X10.50-12	-	B/4PLY	22.51	10.4	-	-	8.5	-	22	1320	-	-	T80423105012
24X9.50-12	-	B/4PLY	23.54	10.08	-	-	7.0	-	24	1375	-	-	T8042495012FP
24X9.50-14	-	B/4PLY	24.0	9.0	-	-	-	-	12	1375	-	-	T8042495014
24X12.00-12	-	B/4PLY	23.23	12.0	-	-	10.5	-	20	1710	-	-	T804120012FP
24X12.00-12	-	B/4PLY	24.0	11.54	-	-	10.5	-	20	1710	-	-	T8042420012
24X12.00-12	-	B/4PLY	23.8	11.5	-	-	-	-	20	1710	-	-	T80424120012
24X12.00-14	-	B/4PLY	24.0	11.8	-	-	-	-	12	1820	-	-	T80424120014
25X8.50-14	-	B/4PLY	24.8	8.58	-	-	7.0	-	22	1650	-	-	T8042585014FP
25X8.50-14	-	C/6PLY	24.77	8.66	-	-	7.0	-	22	1320	-	-	T8062585014FP
25X9.00-12	-	B/4PLY	23.9	9.33	-	-	7.0	-	8	1390	-	-	T8042590012
25X12.00-12	-	B/4PLY	25.0	12.52	-	-	10.5	-	20	1740	-	-	T80425120012
26X10.50-12	-	B/4PLY	26.0	10.5	-	-	8.5	-	22	1590	-	-	T80426105012
26X12.00-12	-	B/4PLY	25.4	12.08	-	-	10.5	-	20	1760	-	-	T80426120012
26X12.00-12	-	C/6PLY	-	-	-	-	-	-	-	-	-	-	T80626120012
26X12.00-16	-	B/4PLY	-	-	-	-	-	-	-	-	-	-	T80426120016FP
31X15.50-15	-	E/10PLY	30.3	14.8	-	-	13.0	-	60	3470	-	-	T801031155015